From 7fa88fc0efe0e46fe5a752735b24d98b1c1b26fe Mon Sep 17 00:00:00 2001
From: Chris Parsons <438676+chrisparsons83@users.noreply.github.com>
Date: Fri, 17 Apr 2026 12:40:08 -0700
Subject: [PATCH] Add projected-wins input mode to admin Elo Ratings page
 (#306)

* Add projected-wins input mode to admin Elo Ratings page

Admins can now enter projected season win totals instead of raw Elo
numbers on the Elo Ratings page. Wins are auto-converted to Elo using
the inverse formula and stored as sourceElo, keeping the rest of the
simulation pipeline unchanged.

- Add `projectedWinsToElo` / `eloToProjectedWins` to probability-engine
- Add `simulator-config.ts` centralising per-sport season length, parity
  factor, and average opponent Elo (AFL, NFL, NBA, NHL, MLB, WNBA)
- Admin Elo Ratings page: toggle between Elo and Projected Wins input
  modes; bulk import parses wins format; existing sourceElo back-fills
  the wins field on load
- AFL simulator now reads sourceElo from participantExpectedValues first,
  falling back to hardcoded TEAMS_DATA then 1400

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Fix lint errors in simulator-config tests and probability-engine

- Replace non-null assertions (`!`) with optional chaining (`?.`) in simulator-config tests
- Remove redundant type annotations on default parameters in probability-engine

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .../admin.sports-seasons.$id.elo-ratings.tsx  | 322 +++++++++++++-----
 .../__tests__/probability-engine.test.ts      |  76 +++++
 app/services/probability-engine.ts            |  75 ++++
 .../__tests__/afl-simulator.test.ts           |  86 ++++-
 .../__tests__/simulator-config.test.ts        |  70 ++++
 app/services/simulations/afl-simulator.ts     |  76 +++--
 app/services/simulations/simulator-config.ts  |  89 +++++
 7 files changed, 672 insertions(+), 122 deletions(-)
 create mode 100644 app/services/simulations/__tests__/simulator-config.test.ts
 create mode 100644 app/services/simulations/simulator-config.ts

diff --git a/app/routes/admin.sports-seasons.$id.elo-ratings.tsx b/app/routes/admin.sports-seasons.$id.elo-ratings.tsx
index 7c0416d..385e911 100644
--- a/app/routes/admin.sports-seasons.$id.elo-ratings.tsx
+++ b/app/routes/admin.sports-seasons.$id.elo-ratings.tsx
@@ -31,6 +31,8 @@ import {
 import { useState } from 'react';
 import { Loader2, CheckCircle2, AlertCircle } from 'lucide-react';
 import { normalizeName } from '~/lib/fuzzy-match';
+import { getSimulatorConfig, supportsProjectedWins } from '~/services/simulations/simulator-config';
+import { eloToProjectedWins, projectedWinsToElo } from '~/services/probability-engine';
 
 // Simulator types that use worldRanking in addition to sourceElo
 const RANKING_SIMULATOR_TYPES = new Set(['darts_bracket', 'cs2_major_qualifying_points']);
@@ -66,7 +68,14 @@ export async function loader({ params }: Route.LoaderArgs) {
 
   const usesRanking = RANKING_SIMULATOR_TYPES.has(sportsSeason.sport?.simulatorType ?? '');
 
-  return { sportsSeason, participants, existingData, usesRanking };
+  const simulatorConfig = sportsSeason.sport?.simulatorType
+    ? getSimulatorConfig(sportsSeason.sport.simulatorType as SimulatorType)
+    : null;
+  const canUseProjectedWins = sportsSeason.sport?.simulatorType
+    ? supportsProjectedWins(sportsSeason.sport.simulatorType as SimulatorType)
+    : false;
+
+  return { sportsSeason, participants, existingData, usesRanking, simulatorConfig, canUseProjectedWins };
 }
 
 interface ActionData {
@@ -85,32 +94,55 @@ export async function action({ request, params }: Route.ActionArgs) {
 
   const participants = await findParticipantsBySportsSeasonId(sportsSeasonId);
   const usesRanking = RANKING_SIMULATOR_TYPES.has(sportsSeason.sport?.simulatorType ?? '');
+  const rawMode = formData.get('inputMode');
+  const inputMode = rawMode === 'projectedWins' ? 'projectedWins' : 'elo';
 
   const eloInputs: Array<{ participantId: string; sportsSeasonId: string; sourceElo: number; worldRanking?: number | null }> = [];
-  for (const participant of participants) {
-    const eloVal = formData.get(`elo_${participant.id}`) as string;
-    const rankVal = formData.get(`rank_${participant.id}`) as string;
 
-    if (eloVal && eloVal.trim() !== '') {
-      const elo = Number(eloVal);
-      if (!isNaN(elo) && elo > 0) {
-        if (usesRanking) {
-          const ranking = rankVal && rankVal.trim() !== '' ? Number(rankVal) : null;
-          eloInputs.push({
-            participantId: participant.id,
-            sportsSeasonId,
-            sourceElo: elo,
-            worldRanking: ranking && !isNaN(ranking) && ranking > 0 ? ranking : null,
-          });
-        } else {
+  if (inputMode === 'projectedWins' && sportsSeason.sport?.simulatorType) {
+    const config = getSimulatorConfig(sportsSeason.sport.simulatorType as SimulatorType);
+    if (!config) {
+      return { success: false, message: 'This sport does not support projected wins input.' };
+    }
+
+    for (const participant of participants) {
+      const winsVal = formData.get(`wins_${participant.id}`) as string;
+      if (winsVal && winsVal.trim() !== '') {
+        const projectedWins = parseFloat(winsVal);
+        if (!isNaN(projectedWins) && projectedWins >= 0 && projectedWins <= config.seasonGames) {
+          const elo = projectedWinsToElo(projectedWins, config.seasonGames, config.parityFactor, config.averageOpponentElo);
           eloInputs.push({ participantId: participant.id, sportsSeasonId, sourceElo: elo });
         }
       }
     }
+  } else {
+    for (const participant of participants) {
+      const eloVal = formData.get(`elo_${participant.id}`) as string;
+      const rankVal = formData.get(`rank_${participant.id}`) as string;
+
+      if (eloVal && eloVal.trim() !== '') {
+        const elo = Number(eloVal);
+        if (!isNaN(elo) && elo > 0) {
+          if (usesRanking) {
+            const ranking = rankVal && rankVal.trim() !== '' ? Number(rankVal) : null;
+            eloInputs.push({
+              participantId: participant.id,
+              sportsSeasonId,
+              sourceElo: elo,
+              worldRanking: ranking && !isNaN(ranking) && ranking > 0 ? ranking : null,
+            });
+          } else {
+            eloInputs.push({ participantId: participant.id, sportsSeasonId, sourceElo: elo });
+          }
+        }
+      }
+    }
   }
 
   if (eloInputs.length === 0) {
-    return { success: false, message: 'Please enter an Elo rating for at least one participant' };
+    return { success: false, message: inputMode === 'projectedWins'
+      ? 'Please enter projected wins for at least one participant'
+      : 'Please enter an Elo rating for at least one participant' };
   }
 
   if (!sportsSeason.sport?.simulatorType) {
@@ -197,10 +229,12 @@ export async function action({ request, params }: Route.ActionArgs) {
 }
 
 export default function AdminSportsSeasonEloRatings() {
-  const { sportsSeason, participants, existingData, usesRanking } = useLoaderData<typeof loader>();
+  const { sportsSeason, participants, existingData, usesRanking, simulatorConfig, canUseProjectedWins } = useLoaderData<typeof loader>();
   const actionData = useActionData<ActionData>();
   const navigation = useNavigation();
 
+  const [inputMode, setInputMode] = useState<'elo' | 'projectedWins'>('elo');
+
   const [eloValues, setEloValues] = useState<Record<string, string>>(() => {
     const initial: Record<string, string> = {};
     participants.forEach(p => {
@@ -219,6 +253,21 @@ export default function AdminSportsSeasonEloRatings() {
     return initial;
   });
 
+  const [winsValues, setWinsValues] = useState<Record<string, string>>(() => {
+    const initial: Record<string, string> = {};
+    if (simulatorConfig) {
+      participants.forEach(p => {
+        const d = existingData[p.id];
+        if (d?.elo !== null && d?.elo !== undefined) {
+          initial[p.id] = eloToProjectedWins(
+            d.elo, simulatorConfig.seasonGames, simulatorConfig.parityFactor, simulatorConfig.averageOpponentElo
+          ).toFixed(1);
+        }
+      });
+    }
+    return initial;
+  });
+
   const [bulkText, setBulkText] = useState('');
   const [parseResults, setParseResults] = useState<{
     matched: Array<{ participantId: string; name: string; elo: number; ranking: number | null; inputName: string }>;
@@ -255,24 +304,43 @@ export default function AdminSportsSeasonEloRatings() {
       const trimmed = line.trim();
       if (!trimmed) continue;
 
-      // Match "Name, Elo" or "Name, Elo, Ranking" (comma/colon/tab separated)
-      const match = usesRanking
-        ? /^(.+?)[\s,:\t]+(\d{3,5})(?:[\s,:\t]+(\d{1,3}))?\s*$/.exec(trimmed)
-        : /^(.+?)[\s,:\t]+(\d{3,5})\s*$/.exec(trimmed);
-      if (!match) continue;
+      if (inputMode === 'projectedWins' && simulatorConfig) {
+        const match = /^(.+?)[\s,:\t]+(\d+(?:\.\d+)?)\s*$/.exec(trimmed);
+        if (!match) continue;
 
-      const inputName = match[1].trim();
-      const elo = parseInt(match[2], 10);
-      const ranking = usesRanking && match[3] ? parseInt(match[3], 10) : null;
+        const inputName = match[1].trim();
+        const projectedWins = parseFloat(match[2]);
 
-      if (isNaN(elo) || elo < 500 || elo > 5000) continue;
+        if (isNaN(projectedWins) || projectedWins < 0 || projectedWins > simulatorConfig.seasonGames) continue;
 
-      const participant = findParticipantMatch(inputName);
-      if (participant && !seen.has(participant.id)) {
-        seen.add(participant.id);
-        matched.push({ participantId: participant.id, name: participant.name, elo, ranking, inputName });
-      } else if (!participant) {
-        unmatched.push({ inputName, elo, ranking });
+        const elo = projectedWinsToElo(projectedWins, simulatorConfig.seasonGames, simulatorConfig.parityFactor, simulatorConfig.averageOpponentElo);
+
+        const participant = findParticipantMatch(inputName);
+        if (participant && !seen.has(participant.id)) {
+          seen.add(participant.id);
+          matched.push({ participantId: participant.id, name: participant.name, elo, ranking: null, inputName });
+        } else if (!participant) {
+          unmatched.push({ inputName, elo, ranking: null });
+        }
+      } else {
+        const match = usesRanking
+          ? /^(.+?)[\s,:\t]+(\d{3,5})(?:[\s,:\t]+(\d{1,3}))?\s*$/.exec(trimmed)
+          : /^(.+?)[\s,:\t]+(\d{3,5})\s*$/.exec(trimmed);
+        if (!match) continue;
+
+        const inputName = match[1].trim();
+        const elo = parseInt(match[2], 10);
+        const ranking = usesRanking && match[3] ? parseInt(match[3], 10) : null;
+
+        if (isNaN(elo) || elo < 500 || elo > 5000) continue;
+
+        const participant = findParticipantMatch(inputName);
+        if (participant && !seen.has(participant.id)) {
+          seen.add(participant.id);
+          matched.push({ participantId: participant.id, name: participant.name, elo, ranking, inputName });
+        } else if (!participant) {
+          unmatched.push({ inputName, elo, ranking });
+        }
       }
     }
 
@@ -283,12 +351,19 @@ export default function AdminSportsSeasonEloRatings() {
     if (!parseResults) return;
     const newElos = { ...eloValues };
     const newRanks = { ...rankValues };
+    const newWins = { ...winsValues };
     for (const m of parseResults.matched) {
       newElos[m.participantId] = m.elo.toString();
       if (m.ranking !== null) newRanks[m.participantId] = m.ranking.toString();
+      if (inputMode === 'projectedWins' && simulatorConfig) {
+        newWins[m.participantId] = eloToProjectedWins(
+          m.elo, simulatorConfig.seasonGames, simulatorConfig.parityFactor, simulatorConfig.averageOpponentElo
+        ).toFixed(1);
+      }
     }
     setEloValues(newElos);
     setRankValues(newRanks);
+    setWinsValues(newWins);
     setParseResults(null);
     setBulkText('');
   }
@@ -318,12 +393,38 @@ export default function AdminSportsSeasonEloRatings() {
         </p>
       </div>
 
+      {/* Input Mode Toggle */}
+      {canUseProjectedWins && !usesRanking && (
+        <div className="mb-6 flex gap-2">
+          <Button
+            type="button"
+            variant={inputMode === 'elo' ? 'default' : 'outline'}
+            onClick={() => setInputMode('elo')}
+          >
+            Elo Ratings
+          </Button>
+          <Button
+            type="button"
+            variant={inputMode === 'projectedWins' ? 'default' : 'outline'}
+            onClick={() => setInputMode('projectedWins')}
+          >
+            Projected Wins
+          </Button>
+        </div>
+      )}
+
       {/* Bulk Import */}
       <Card className="mb-6">
         <CardHeader>
           <CardTitle>Bulk Import</CardTitle>
           <CardDescription>
-            {usesRanking ? (
+            {inputMode === 'projectedWins' && simulatorConfig ? (
+              <>
+                Paste projected season wins one per line. Format: <code>Team Name, 15.6</code>.
+                Wins are automatically converted to Elo ratings using {simulatorConfig.seasonGames} total games
+                and parity factor {simulatorConfig.parityFactor}. Names are fuzzy-matched to participants.
+              </>
+            ) : usesRanking ? (
               <>
                 Paste one entry per line. Format:{' '}
                 <code>Name, Elo, {rankLabel}</code> (ranking is optional — omit it and the simulator
@@ -340,11 +441,13 @@ export default function AdminSportsSeasonEloRatings() {
         <CardContent className="space-y-4">
           <Textarea
             placeholder={
-              usesRanking
-                ? simulatorType === 'cs2_major_qualifying_points'
-                  ? `Natus Vincere, 1850, 1\nFaZe Clan, 1820, 2\nVitality, 1810, 3`
-                  : `Luke Littler, 2099, 1\nMichael van Gerwen, 1950, 2\nLuke Humphries, 1947, 3`
-                : `Judd Trump, 2594\nRonnie O'Sullivan, 2441\nMark Selby, 2432`
+              inputMode === 'projectedWins'
+                ? `Team Name, 15.6\nTeam Name, 14.5\nTeam Name, 13.8`
+                : usesRanking
+                  ? simulatorType === 'cs2_major_qualifying_points'
+                    ? `Natus Vincere, 1850, 1\nFaZe Clan, 1820, 2\nVitality, 1810, 3`
+                    : `Luke Littler, 2099, 1\nMichael van Gerwen, 1950, 2\nLuke Humphries, 1947, 3`
+                  : `Judd Trump, 2594\nRonnie O'Sullivan, 2441\nMark Selby, 2432`
             }
             value={bulkText}
             onChange={e => { setBulkText(e.target.value); setParseResults(null); }}
@@ -411,59 +514,96 @@ export default function AdminSportsSeasonEloRatings() {
         <Card>
           <CardHeader>
             <CardTitle>
-              {usesRanking ? `Player Elo & ${rankLabel}s` : 'Player Elo Ratings'}
+              {inputMode === 'projectedWins'
+                ? `Projected Season Wins (out of ${simulatorConfig?.seasonGames ?? '?'})`
+                : usesRanking
+                  ? `Player Elo & ${rankLabel}s`
+                  : 'Player Elo Ratings'}
             </CardTitle>
             <CardDescription>
-              {usesRanking
-                ? `Enter each player's Elo and ${rankLabel}. Saving will automatically run the simulation and update expected values.`
-                : 'Enter each player\'s current Elo rating. Saving will automatically run the simulation and update expected values.'}
+              {inputMode === 'projectedWins'
+                ? 'Enter each team\'s projected total season wins. Converted to Elo automatically. Saving will run the simulation and update expected values.'
+                : usesRanking
+                  ? `Enter each player's Elo and ${rankLabel}. Saving will automatically run the simulation and update expected values.`
+                  : 'Enter each player\'s current Elo rating. Saving will automatically run the simulation and update expected values.'}
             </CardDescription>
           </CardHeader>
           <CardContent>
             <Form method="post" className="space-y-4">
-              {usesRanking && (
+              <input type="hidden" name="inputMode" value={inputMode} />
+              {usesRanking && inputMode === 'elo' && (
                 <div className="grid grid-cols-[1fr_100px_90px] gap-x-3 gap-y-1 items-center text-xs font-medium text-muted-foreground">
                   <span>Player</span>
                   <span>Elo</span>
                   <span>{rankLabel} #</span>
                 </div>
               )}
+              {inputMode === 'projectedWins' && (
+                <div className="grid grid-cols-[1fr_100px] gap-x-3 gap-y-1 items-center text-xs font-medium text-muted-foreground">
+                  <span>Team</span>
+                  <span>Proj Wins</span>
+                </div>
+              )}
               <div className="space-y-2">
-                {sortedParticipants.map(participant => (
-                  <div
-                    key={participant.id}
-                    className={usesRanking
-                      ? 'grid grid-cols-[1fr_100px_90px] gap-x-3 items-center'
-                      : 'grid grid-cols-2 gap-4 items-center'}
-                  >
-                    <Label htmlFor={`elo_${participant.id}`} className="truncate text-sm">
-                      {participant.name}
-                    </Label>
-                    <Input
-                      type="number"
-                      id={`elo_${participant.id}`}
-                      name={`elo_${participant.id}`}
-                      placeholder={usesRanking ? '1800' : '2450'}
-                      value={eloValues[participant.id] ?? ''}
-                      onChange={e =>
-                        setEloValues(prev => ({ ...prev, [participant.id]: e.target.value }))
-                      }
-                      className={usesRanking ? 'h-8 text-sm' : undefined}
-                    />
-                    {usesRanking && (
+                {sortedParticipants.map(participant => {
+                  if (inputMode === 'projectedWins' && simulatorConfig) {
+                    return (
+                      <div key={participant.id} className="grid grid-cols-[1fr_100px] gap-x-3 items-center">
+                        <Label htmlFor={`wins_${participant.id}`} className="truncate text-sm">
+                          {participant.name}
+                        </Label>
+                        <Input
+                          type="number"
+                          step="0.1"
+                          id={`wins_${participant.id}`}
+                          name={`wins_${participant.id}`}
+                          placeholder={`${(simulatorConfig.seasonGames / 2).toFixed(1)}`}
+                          value={winsValues[participant.id] ?? ''}
+                          onChange={e =>
+                            setWinsValues(prev => ({ ...prev, [participant.id]: e.target.value }))
+                          }
+                          className="h-8 text-sm"
+                        />
+                      </div>
+                    );
+                  }
+
+                  return (
+                    <div
+                      key={participant.id}
+                      className={usesRanking
+                        ? 'grid grid-cols-[1fr_100px_90px] gap-x-3 items-center'
+                        : 'grid grid-cols-2 gap-4 items-center'}
+                    >
+                      <Label htmlFor={`elo_${participant.id}`} className="truncate text-sm">
+                        {participant.name}
+                      </Label>
                       <Input
                         type="number"
-                        name={`rank_${participant.id}`}
-                        placeholder="—"
-                        value={rankValues[participant.id] ?? ''}
+                        id={`elo_${participant.id}`}
+                        name={`elo_${participant.id}`}
+                        placeholder={usesRanking ? '1800' : '2450'}
+                        value={eloValues[participant.id] ?? ''}
                         onChange={e =>
-                          setRankValues(prev => ({ ...prev, [participant.id]: e.target.value }))
+                          setEloValues(prev => ({ ...prev, [participant.id]: e.target.value }))
                         }
-                        className="h-8 text-sm"
+                        className={usesRanking ? 'h-8 text-sm' : undefined}
                       />
-                    )}
-                  </div>
-                ))}
+                      {usesRanking && (
+                        <Input
+                          type="number"
+                          name={`rank_${participant.id}`}
+                          placeholder="—"
+                          value={rankValues[participant.id] ?? ''}
+                          onChange={e =>
+                            setRankValues(prev => ({ ...prev, [participant.id]: e.target.value }))
+                          }
+                          className="h-8 text-sm"
+                        />
+                      )}
+                    </div>
+                  );
+                })}
               </div>
 
               {actionData && !actionData.success && actionData.message && (
@@ -483,19 +623,35 @@ export default function AdminSportsSeasonEloRatings() {
             <CardTitle>How It Works</CardTitle>
           </CardHeader>
           <CardContent className="text-sm space-y-2">
-            <ol className="list-decimal list-inside space-y-2">
-              <li>Save Elo ratings{usesRanking ? ` and ${rankLabel}s` : ''} for all participants</li>
-              <li>Compute per-game win probability from Elo difference</li>
-              <li>Compute match win probability using the Bernoulli model for each round's format</li>
-              <li>Run Monte Carlo simulations of the full event</li>
-              <li>Distribute probabilities across 1st–8th place buckets</li>
-              <li>Calculate expected fantasy value per player</li>
-            </ol>
-            {usesRanking && (
+            {inputMode === 'projectedWins' ? (
+              <ol className="list-decimal list-inside space-y-2">
+                <li>Enter each team's projected total season wins</li>
+                <li>Wins are converted to Elo ratings using the inverse Elo formula</li>
+                <li>Elo ratings are saved and the simulation runs automatically</li>
+                <li>Results: probability distributions across 1st–8th place buckets</li>
+                <li>Expected fantasy value is calculated per team</li>
+              </ol>
+            ) : (
+              <ol className="list-decimal list-inside space-y-2">
+                <li>Save Elo ratings{usesRanking ? ` and ${rankLabel}s` : ''} for all participants</li>
+                <li>Compute per-game win probability from Elo difference</li>
+                <li>Compute match win probability using the Bernoulli model for each round's format</li>
+                <li>Run Monte Carlo simulations of the full event</li>
+                <li>Distribute probabilities across 1st–8th place buckets</li>
+                <li>Calculate expected fantasy value per player</li>
+              </ol>
+            )}
+            {usesRanking && inputMode === 'elo' && (
               <div className="mt-4 text-muted-foreground text-xs">
                 {rankLabel} is optional — if omitted, the simulator uses Elo order for seeding.
               </div>
             )}
+            {inputMode === 'projectedWins' && simulatorConfig && (
+              <div className="mt-4 text-muted-foreground text-xs">
+                Conversion: Elo = {simulatorConfig.averageOpponentElo} &minus; {simulatorConfig.parityFactor} &times; log&#8321;&#8320;((1 &minus; winRate) / winRate),
+                where winRate = projectedWins / {simulatorConfig.seasonGames}.
+              </div>
+            )}
           </CardContent>
         </Card>
       </div>
diff --git a/app/services/__tests__/probability-engine.test.ts b/app/services/__tests__/probability-engine.test.ts
index 2917801..0be8743 100644
--- a/app/services/__tests__/probability-engine.test.ts
+++ b/app/services/__tests__/probability-engine.test.ts
@@ -8,6 +8,8 @@ import {
   eloWinProbability,
   convertFuturesToElo,
   calculatePredictionError,
+  projectedWinsToElo,
+  eloToProjectedWins,
 } from '../probability-engine';
 
 describe('probability-engine', () => {
@@ -319,4 +321,78 @@ describe('probability-engine', () => {
       expect(error).toBeLessThan(0.25); // 25% tolerance before calibration
     });
   });
+
+  describe('projectedWinsToElo', () => {
+    it('converts average projected wins to 1500 Elo', () => {
+      // 11.5 wins out of 23 = 0.5 win rate = 1500 Elo
+      expect(projectedWinsToElo(11.5, 23, 450)).toBe(1500);
+    });
+
+    it('converts AFL 2026 Bulldogs (15.6 wins / 23) to ~1646 Elo', () => {
+      expect(projectedWinsToElo(15.6, 23, 450)).toBe(1646);
+    });
+
+    it('converts AFL 2026 Essendon (7.1 wins / 23) to ~1342 Elo', () => {
+      expect(projectedWinsToElo(7.1, 23, 450)).toBe(1342);
+    });
+
+    it('higher projected wins produce higher Elo', () => {
+      const elo10 = projectedWinsToElo(10, 23, 450);
+      const elo15 = projectedWinsToElo(15, 23, 450);
+      expect(elo15).toBeGreaterThan(elo10);
+    });
+
+    it('uses parity factor 400 as default', () => {
+      // NFL-like: 8.5/17 = 0.5 → 1500
+      expect(projectedWinsToElo(8.5, 17)).toBe(1500);
+    });
+
+    it('handles 0 projected wins (floor)', () => {
+      const elo = projectedWinsToElo(0, 23, 450);
+      expect(elo).toBeLessThan(1000);
+    });
+
+    it('handles max projected wins (cap)', () => {
+      const elo = projectedWinsToElo(23, 23, 450);
+      expect(elo).toBeGreaterThan(2500);
+    });
+
+    it('is inverse of eloToProjectedWins (round-trip)', () => {
+      const wins = 14.3;
+      const elo = projectedWinsToElo(wins, 23, 450);
+      const roundTrip = eloToProjectedWins(elo, 23, 450);
+      expect(roundTrip).toBeCloseTo(wins, 0);
+    });
+
+    it('throws for negative projected wins', () => {
+      expect(() => projectedWinsToElo(-1, 23, 450)).toThrow('between 0 and');
+    });
+
+    it('throws for projected wins exceeding total games', () => {
+      expect(() => projectedWinsToElo(25, 23, 450)).toThrow('between 0 and');
+    });
+
+    it('throws for zero total games', () => {
+      expect(() => projectedWinsToElo(5, 0, 450)).toThrow('must be positive');
+    });
+  });
+
+  describe('eloToProjectedWins', () => {
+    it('returns half the season for 1500 Elo (average)', () => {
+      expect(eloToProjectedWins(1500, 23, 450)).toBeCloseTo(11.5, 1);
+    });
+
+    it('returns more wins for higher Elo', () => {
+      const winsHigh = eloToProjectedWins(1700, 23, 450);
+      const winsLow = eloToProjectedWins(1300, 23, 450);
+      expect(winsHigh).toBeGreaterThan(winsLow);
+    });
+
+    it('round-trips with projectedWinsToElo', () => {
+      const elo = 1600;
+      const wins = eloToProjectedWins(elo, 23, 450);
+      const roundTrip = projectedWinsToElo(wins, 23, 450);
+      expect(roundTrip).toBe(elo);
+    });
+  });
 });
diff --git a/app/services/probability-engine.ts b/app/services/probability-engine.ts
index 2f8549f..e7c7629 100644
--- a/app/services/probability-engine.ts
+++ b/app/services/probability-engine.ts
@@ -293,3 +293,78 @@ export function calculatePredictionError(
 
   return { meanError, maxError };
 }
+
+/**
+ * Convert projected season win totals to an Elo rating.
+ *
+ * Given a team's projected total wins (including games already played),
+ * derives the Elo rating that would produce that win rate against an
+ * average opponent over the full season.
+ *
+ * Inverse of the Elo win probability formula:
+ *   elo = avgElo - parityFactor × log₁₀((1 − winRate) / winRate)
+ *   where winRate = projectedWins / totalGames
+ *
+ * @param projectedWins Total projected wins for the season (e.g. 15.6)
+ * @param totalGames Total regular season games (e.g. 23 for AFL)
+ * @param parityFactor Elo parity factor for the sport (e.g. 450 for AFL)
+ * @param averageElo Elo of an average opponent (typically 1500)
+ * @returns Elo rating (rounded to integer)
+ *
+ * @example
+ * projectedWinsToElo(15.6, 23, 450)  // 1646 (Western Bulldogs 2026)
+ * projectedWinsToElo(11.5, 23, 450)  // 1500 (average team)
+ * projectedWinsToElo(7.1, 23, 450)   // 1342 (Essendon 2026)
+ */
+export function projectedWinsToElo(
+  projectedWins: number,
+  totalGames: number,
+  parityFactor = 400,
+  averageElo = 1500
+): number {
+  if (totalGames <= 0) {
+    throw new Error('Total games must be positive');
+  }
+  if (parityFactor <= 0) {
+    throw new Error('Parity factor must be positive');
+  }
+  if (projectedWins < 0 || projectedWins > totalGames) {
+    throw new Error(
+      `Projected wins (${projectedWins}) must be between 0 and total games (${totalGames})`
+    );
+  }
+
+  const winRate = projectedWins / totalGames;
+
+  // Edge cases: clamp to avoid log(0) or division by zero
+  if (winRate >= 1.0) return averageElo + parityFactor * 3; // ~dominant cap
+  if (winRate <= 0.0) return averageElo - parityFactor * 3; // ~terrible floor
+
+  const elo = averageElo - parityFactor * Math.log10((1 - winRate) / winRate);
+  return Math.round(elo);
+}
+
+/**
+ * Convert an Elo rating back to projected season wins.
+ *
+ * This is the forward direction of projectedWinsToElo:
+ *   winRate = 1 / (1 + 10^((averageElo - elo) / parityFactor))
+ *   projectedWins = winRate × totalGames
+ *
+ * Useful for displaying the equivalent projected wins for a given Elo rating.
+ *
+ * @param elo Elo rating
+ * @param totalGames Total regular season games
+ * @param parityFactor Elo parity factor
+ * @param averageElo Elo of an average opponent
+ * @returns Projected wins (decimal, e.g. 15.6)
+ */
+export function eloToProjectedWins(
+  elo: number,
+  totalGames: number,
+  parityFactor = 400,
+  averageElo = 1500
+): number {
+  const winProb = 1 / (1 + Math.pow(10, (averageElo - elo) / parityFactor));
+  return winProb * totalGames;
+}
diff --git a/app/services/simulations/__tests__/afl-simulator.test.ts b/app/services/simulations/__tests__/afl-simulator.test.ts
index c7bbff4..56d7025 100644
--- a/app/services/simulations/__tests__/afl-simulator.test.ts
+++ b/app/services/simulations/__tests__/afl-simulator.test.ts
@@ -132,11 +132,25 @@ describe("AFLSimulator.simulate()", () => {
     const { database } = await import("~/database/context");
     const { getRegularSeasonStandings } = await import("~/models/regular-season-standings");
 
+    const participantRows = PARTICIPANT_ROWS;
+
+    let selectCallCount = 0;
     mockDb = {
-      select: vi.fn().mockReturnValue({
-        from: vi.fn().mockReturnValue({
-          where: vi.fn().mockResolvedValue(PARTICIPANT_ROWS),
-        }),
+      select: vi.fn().mockImplementation(() => {
+        selectCallCount++;
+        if (selectCallCount === 1) {
+          return {
+            from: vi.fn().mockReturnValue({
+              where: vi.fn().mockResolvedValue(participantRows),
+            }),
+          };
+        }
+        // Second call: sourceElo query (no DB Elo by default)
+        return {
+          from: vi.fn().mockReturnValue({
+            where: vi.fn().mockResolvedValue([]),
+          }),
+        };
       }),
     };
 
@@ -146,10 +160,21 @@ describe("AFLSimulator.simulate()", () => {
   });
 
   it("throws if no participants found", async () => {
-    mockDb.select.mockReturnValue({
-      from: vi.fn().mockReturnValue({
-        where: vi.fn().mockResolvedValue([]),
-      }),
+    let selectCallCount = 0;
+    mockDb.select.mockImplementation(() => {
+      selectCallCount++;
+      if (selectCallCount === 1) {
+        return {
+          from: vi.fn().mockReturnValue({
+            where: vi.fn().mockResolvedValue([]),
+          }),
+        };
+      }
+      return {
+        from: vi.fn().mockReturnValue({
+          where: vi.fn().mockResolvedValue([]),
+        }),
+      };
     });
     const sim = new AFLSimulator();
     await expect(sim.simulate("season-1")).rejects.toThrow(/No participants found/);
@@ -285,4 +310,49 @@ describe("AFLSimulator.simulate()", () => {
 
     expect(leader.probabilities.probFirst).toBeGreaterThan(bottom.probabilities.probFirst);
   });
+
+  it("DB sourceElo overrides hardcoded TEAMS_DATA values", async () => {
+    // Set DB Elo for West Coast (team-18) to 1800 (higher than Bulldogs)
+    let selectCallCount = 0;
+    mockDb.select.mockImplementation(() => {
+      selectCallCount++;
+      if (selectCallCount === 1) {
+        return {
+          from: vi.fn().mockReturnValue({
+            where: vi.fn().mockResolvedValue(PARTICIPANT_ROWS),
+          }),
+        };
+      }
+      return {
+        from: vi.fn().mockReturnValue({
+          where: vi.fn().mockResolvedValue([
+            { participantId: "team-18", sourceElo: 1800 },
+          ]),
+        }),
+      };
+    });
+
+    const sim = new AFLSimulator();
+    const results = await sim.simulate("season-1");
+
+    const westCoast = results.find((r) => r.participantId === "team-18");
+    const bulldogs = results.find((r) => r.participantId === "team-1");
+    if (!westCoast || !bulldogs) throw new Error("Expected results not found");
+
+    // With DB Elo 1800, West Coast should now be favored over Bulldogs (1646)
+    expect(westCoast.probabilities.probFirst).toBeGreaterThan(bulldogs.probabilities.probFirst);
+  });
+
+  it("falls back to hardcoded TEAMS_DATA when no DB sourceElo exists", async () => {
+    // Default mock already returns no sourceElo rows — should use TEAMS_DATA
+    const sim = new AFLSimulator();
+    const results = await sim.simulate("season-1");
+
+    const bulldogs = results.find((r) => r.participantId === "team-1");
+    const westCoast = results.find((r) => r.participantId === "team-18");
+    if (!bulldogs || !westCoast) throw new Error("Expected results not found");
+
+    // Bulldogs (1646) should still be favored over West Coast (1362) from hardcoded data
+    expect(bulldogs.probabilities.probFirst).toBeGreaterThan(westCoast.probabilities.probFirst);
+  });
 });
diff --git a/app/services/simulations/__tests__/simulator-config.test.ts b/app/services/simulations/__tests__/simulator-config.test.ts
new file mode 100644
index 0000000..fb7f0d8
--- /dev/null
+++ b/app/services/simulations/__tests__/simulator-config.test.ts
@@ -0,0 +1,70 @@
+import { describe, it, expect } from "vitest";
+import { getSimulatorConfig, supportsProjectedWins } from "../simulator-config";
+
+describe("simulator-config", () => {
+  describe("getSimulatorConfig", () => {
+    it("returns config for afl_bracket", () => {
+      const config = getSimulatorConfig("afl_bracket");
+      expect(config).not.toBeNull();
+      expect(config?.seasonGames).toBe(23);
+      expect(config?.parityFactor).toBe(450);
+      expect(config?.averageOpponentElo).toBe(1500);
+    });
+
+    it("returns config for nfl_bracket", () => {
+      const config = getSimulatorConfig("nfl_bracket");
+      expect(config).not.toBeNull();
+      expect(config?.seasonGames).toBe(17);
+      expect(config?.parityFactor).toBe(400);
+    });
+
+    it("returns config for nba_bracket", () => {
+      const config = getSimulatorConfig("nba_bracket");
+      expect(config).not.toBeNull();
+      expect(config?.seasonGames).toBe(82);
+    });
+
+    it("returns config for nhl_bracket", () => {
+      const config = getSimulatorConfig("nhl_bracket");
+      expect(config).not.toBeNull();
+      expect(config?.seasonGames).toBe(82);
+      expect(config?.parityFactor).toBe(1000);
+    });
+
+    it("returns config for mlb_bracket", () => {
+      const config = getSimulatorConfig("mlb_bracket");
+      expect(config).not.toBeNull();
+      expect(config?.seasonGames).toBe(162);
+    });
+
+    it("returns null for snooker_bracket", () => {
+      expect(getSimulatorConfig("snooker_bracket")).toBeNull();
+    });
+
+    it("returns null for darts_bracket", () => {
+      expect(getSimulatorConfig("darts_bracket")).toBeNull();
+    });
+
+    it("returns null for playoff_bracket", () => {
+      expect(getSimulatorConfig("playoff_bracket")).toBeNull();
+    });
+  });
+
+  describe("supportsProjectedWins", () => {
+    it("returns true for afl_bracket", () => {
+      expect(supportsProjectedWins("afl_bracket")).toBe(true);
+    });
+
+    it("returns true for nfl_bracket", () => {
+      expect(supportsProjectedWins("nfl_bracket")).toBe(true);
+    });
+
+    it("returns false for snooker_bracket", () => {
+      expect(supportsProjectedWins("snooker_bracket")).toBe(false);
+    });
+
+    it("returns false for darts_bracket", () => {
+      expect(supportsProjectedWins("darts_bracket")).toBe(false);
+    });
+  });
+});
diff --git a/app/services/simulations/afl-simulator.ts b/app/services/simulations/afl-simulator.ts
index 36dc54f..5616844 100644
--- a/app/services/simulations/afl-simulator.ts
+++ b/app/services/simulations/afl-simulator.ts
@@ -5,8 +5,9 @@
  *
  * Algorithm:
  *   1. Load all participants for the sports season from DB
- *   2. Load current regular season standings (wins, gamesPlayed) — if available
- *   3. Match participant names to hardcoded team data (Elo ratings)
+ *   2. Load Elo ratings from participantExpectedValues.sourceElo (admin-maintained)
+ *      Falls back to hardcoded TEAMS_DATA (Squiggle-derived) if no sourceElo set.
+ *   3. Load current regular season standings (wins, gamesPlayed) — if available
  *   4. For each simulation:
  *      a. For each team, simulate remaining regular season games (TOTAL_GAMES - gamesPlayed)
  *         using Elo win probability vs. an average opponent (Elo 1500)
@@ -36,12 +37,14 @@
  *   Per-game win probability = eloWinProbability(teamElo, 1500) where 1500 = average opponent.
  *   If no standings exist in DB, defaults to 0 wins / TOTAL_GAMES remaining (seeding by Elo only).
  *
- * Elo ratings (see TEAMS_DATA below):
- *   Backsolved from Squiggle's projected season win totals using the inverse formula:
+ * Elo ratings:
+ *   Priority: sourceElo from participantExpectedValues (admin UI) → hardcoded TEAMS_DATA
+ *   → fallback 1400.
+ *   Admin can enter Elo directly or via "Projected Wins" mode on the Elo Ratings admin page,
+ *   which auto-converts projected season wins to Elo using the inverse formula:
  *     elo = 1500 - 450 × log₁₀((1 − wins/23) / (wins/23))
- *   Projected win counts were read from a screenshot of squiggle.com.au's season
- *   simulation table (as of Round 2, 2026). Update each round as projections shift.
- *   Source: https://squiggle.com.au
+ *   The hardcoded TEAMS_DATA values are backsolved from Squiggle's projected season
+ *   win totals (as of Round 2, 2026). Source: https://squiggle.com.au
  *
  * Placement tiers → SimulationProbabilities mapping:
  *   probFirst          = Grand Final winner (1 per sim)
@@ -83,16 +86,13 @@ const AFL_REGULAR_SEASON_GAMES = 23;
 /** Average opponent Elo used for regular season projections. */
 const AVERAGE_OPPONENT_ELO = 1500;
 
-// ─── Team data (2026 AFL season, as of end of Round 2) ───────────────────────
+// ─── Hardcoded team data (FALLBACK — used only when no sourceElo in DB) ──────
 //
 // Elo ratings are backsolved from Squiggle's projected season win totals.
-// Process: we screenshotted squiggle.com.au's season simulation table (Round 2,
-// 2026), read each team's projected wins, then applied the inverse formula:
-//   elo = 1500 - 450 × log₁₀((1 − wins/23) / (wins/23))
-// This calibrates each team so the simulator reproduces Squiggle's ladder
-// projection when every game is played against an average opponent (Elo 1500).
-// Update each round by re-reading the projected wins from Squiggle and recalculating.
-// Source: https://squiggle.com.au
+// These serve as fallback defaults when no sourceElo has been entered via the
+// admin Elo Ratings page. Prefer updating via Admin → Elo Ratings (projected
+// wins mode) rather than editing these values.
+// Source: https://squiggle.com.au (Round 2, 2026)
 
 interface AflTeamData {
   elo: number;
@@ -169,7 +169,8 @@ export function eloWinProbability(eloA: number, eloB: number): number {
 interface TeamEntry {
   id: string;
   name: string;
-  data: AflTeamData | undefined;
+  /** Resolved Elo: DB sourceElo > hardcoded TEAMS_DATA > fallback 1400. */
+  elo: number;
   /** Actual wins from the standings table (0 if no standings loaded). */
   currentWins: number;
   /** Remaining regular season games = TOTAL_GAMES - gamesPlayed (0 if season is complete). */
@@ -178,12 +179,6 @@ interface TeamEntry {
   winProb: number;
 }
 
-/** Get Elo for a team entry.
- *  Fallback 1400 = conservative below-average estimate for unknown/unrecognized teams. */
-function elo(entry: TeamEntry): number {
-  return entry.data?.elo ?? 1400;
-}
-
 /** Simulate remaining regular season games for a team.
  *  Returns projected total wins for the season. */
 function simulateProjectedWins(entry: TeamEntry): number {
@@ -200,12 +195,19 @@ export class AFLSimulator implements Simulator {
   async simulate(sportsSeasonId: string): Promise<SimulationResult[]> {
     const db = database();
 
-    // 1. Load participants and standings in parallel.
-    const [participantRows, standings] = await Promise.all([
+    // 1. Load participants, DB Elo, and standings in parallel.
+    const [participantRows, evRows, standings] = await Promise.all([
       db
         .select({ id: schema.participants.id, name: schema.participants.name })
         .from(schema.participants)
         .where(eq(schema.participants.sportsSeasonId, sportsSeasonId)),
+      db
+        .select({
+          participantId: schema.participantExpectedValues.participantId,
+          sourceElo: schema.participantExpectedValues.sourceElo,
+        })
+        .from(schema.participantExpectedValues)
+        .where(eq(schema.participantExpectedValues.sportsSeasonId, sportsSeasonId)),
       getRegularSeasonStandings(sportsSeasonId),
     ]);
 
@@ -223,7 +225,16 @@ export class AFLSimulator implements Simulator {
       );
     }
 
-    // 2. Build standings lookup and construct team entries.
+    // 2. Build Elo map from DB sourceElo values.
+    const dbEloMap = new Map<string, number>();
+    for (const row of evRows) {
+      if (row.sourceElo !== null && row.sourceElo !== undefined) {
+        dbEloMap.set(row.participantId, row.sourceElo);
+      }
+    }
+
+    // 3. Build standings lookup and construct team entries.
+    //    Elo priority: DB sourceElo → hardcoded TEAMS_DATA → fallback 1400.
     //    currentWins, remainingGames, and per-game winProb are all resolved once
     //    here so nothing is recomputed inside the hot simulation loop.
     const standingsMap = new Map(standings.map((s) => [s.participantId, s]));
@@ -231,22 +242,25 @@ export class AFLSimulator implements Simulator {
 
     const teams: TeamEntry[] = participantRows.map((r) => {
       const standing = standingsMap.get(r.id);
-      const data = getTeamData(r.name);
-      if (!data) {
+      const dbElo = dbEloMap.get(r.id);
+      const fallbackData = getTeamData(r.name);
+      const resolvedElo = dbElo ?? fallbackData?.elo ?? 1400;
+
+      if (dbElo === undefined && !fallbackData) {
         logger.warn(
           { participantName: r.name, sportsSeasonId },
           `AFL simulator: no Elo found for participant "${r.name}" — falling back to 1400. ` +
-            `Add an entry to TEAMS_DATA or rename the participant to match an existing key.`
+            `Enter Elo via Admin → Elo Ratings or rename the participant to match a TEAMS_DATA key.`
         );
       }
       const gamesPlayed = standing?.gamesPlayed ?? 0;
       return {
         id: r.id,
         name: r.name,
-        data,
+        elo: resolvedElo,
         currentWins: standing?.wins ?? 0,
         remainingGames: Math.max(0, AFL_REGULAR_SEASON_GAMES - gamesPlayed),
-        winProb: eloWinProbability(data?.elo ?? 1400, AVERAGE_OPPONENT_ELO),
+        winProb: eloWinProbability(resolvedElo, AVERAGE_OPPONENT_ELO),
       };
     });
 
@@ -254,7 +268,7 @@ export class AFLSimulator implements Simulator {
 
     /** Simulate a single AFL game. Returns the winner. */
     const simGame = (a: TeamEntry, b: TeamEntry): TeamEntry =>
-      Math.random() < eloWinProbability(elo(a), elo(b)) ? a : b;
+      Math.random() < eloWinProbability(a.elo, b.elo) ? a : b;
 
     /**
      * Project end-of-season ladder and return the top 10 finalists seeded 1–10.
diff --git a/app/services/simulations/simulator-config.ts b/app/services/simulations/simulator-config.ts
new file mode 100644
index 0000000..ad921b3
--- /dev/null
+++ b/app/services/simulations/simulator-config.ts
@@ -0,0 +1,89 @@
+/**
+ * Simulator Configuration
+ *
+ * Per-sport parameters used by simulators and admin UI tools.
+ * Centralizes season length, parity factors, and other sport-specific
+ * constants so they can be shared between simulators and the Elo Ratings
+ * admin page (e.g., for projected wins → Elo conversion).
+ */
+
+import type { SimulatorType } from "./registry";
+
+export interface SimulatorConfig {
+  /** Total regular season games per team in this sport. */
+  seasonGames: number;
+  /** Elo parity factor for single-game win probability.
+   *  P(A) = 1 / (1 + 10^((eloB - eloA) / parityFactor))
+   *  Higher = more unpredictable per game. */
+  parityFactor: number;
+  /** Average opponent Elo — used for season projections against a generic opponent. */
+  averageOpponentElo: number;
+}
+
+const CONFIG: Record<SimulatorType, SimulatorConfig | null> = {
+  afl_bracket: {
+    seasonGames: 23,
+    parityFactor: 450,
+    averageOpponentElo: 1500,
+  },
+  nfl_bracket: {
+    seasonGames: 17,
+    parityFactor: 400,
+    averageOpponentElo: 1500,
+  },
+  nba_bracket: {
+    seasonGames: 82,
+    parityFactor: 400,
+    averageOpponentElo: 1500,
+  },
+  nhl_bracket: {
+    seasonGames: 82,
+    // NHL is the highest-parity major North American league — roughly 1 in 3 games
+    // goes to overtime/shootout and favourites win far less reliably than in NBA/NFL.
+    // 1000 was calibrated so that a team projected at 55 wins (67%) maps to ~1570 Elo,
+    // which keeps the spread tight and reflects the empirical upset rate.
+    parityFactor: 1000,
+    averageOpponentElo: 1500,
+  },
+  mlb_bracket: {
+    seasonGames: 162,
+    parityFactor: 400,
+    averageOpponentElo: 1500,
+  },
+  wnba_bracket: {
+    seasonGames: 44,
+    parityFactor: 400,
+    averageOpponentElo: 1500,
+  },
+  // Simulators below don't use projected-wins → Elo conversion.
+  // They can be populated later if needed.
+  f1_standings: null,
+  indycar_standings: null,
+  golf_qualifying_points: null,
+  playoff_bracket: null,
+  ucl_bracket: null,
+  ncaam_bracket: null,
+  ncaaw_bracket: null,
+  snooker_bracket: null,
+  tennis_qualifying_points: null,
+  world_cup: null,
+  darts_bracket: null,
+  cs2_major_qualifying_points: null,
+  ncaa_football_bracket: null,
+  llws_bracket: null,
+};
+
+/**
+ * Get the simulator config for a given simulator type.
+ * Returns null for simulator types that don't have season-game / Elo config.
+ */
+export function getSimulatorConfig(simulatorType: SimulatorType): SimulatorConfig | null {
+  return CONFIG[simulatorType];
+}
+
+/**
+ * Check if a simulator type supports projected-wins → Elo conversion.
+ */
+export function supportsProjectedWins(simulatorType: SimulatorType): boolean {
+  return CONFIG[simulatorType] !== null;
+}