Add gWAR (Grove WAR) calculation system with Baseball Savant integration

backend/src/main/java/com/mlbstats/api/controller/IngestionController.java

@@ -191,6 +191,20 @@ public ResponseEntity<SyncJobDto> syncLinescores(
         return ResponseEntity.ok(SyncJobDto.fromEntity(job));
     }
 
+    @PostMapping("/sabermetrics")
+    @Operation(summary = "Sync sabermetrics", description = "Synchronizes WAR, wOBA, FIP, expected stats, and calculates gWAR")
+    public ResponseEntity<SyncJobDto> syncSabermetrics(
+            @RequestParam(required = false) Integer season,
+            @AuthenticationPrincipal OAuth2User principal) {
+
+        if (season == null) {
+            season = DateUtils.getCurrentSeason();
+        }
+        AppUser user = getUserFromPrincipal(principal);
+        SyncJob job = orchestrator.createAndRunTrackedSabermetricsSync(season, TriggerType.MANUAL, user);
+        return ResponseEntity.ok(SyncJobDto.fromEntity(job));
+    }
+
     // ===== Legacy Untracked Endpoints =====
 
     @PostMapping("/players/incomplete")

backend/src/main/java/com/mlbstats/api/controller/PlayerController.java

@@ -319,4 +319,40 @@ public ResponseEntity<PlayerComparisonDto> comparePlayers(
 
         return ResponseEntity.ok(playerApiService.comparePlayerStats(playerIds, seasonList, careerMode));
     }
+
+    // ================================================================================
+    // gWAR (Grove WAR) Endpoints
+    // ================================================================================
+
+    @GetMapping("/leaders/gwar/batting")
+    @Operation(summary = "Get batting gWAR leaders", description = "Returns top position players by gWAR (Grove WAR) for a season")
+    public ResponseEntity<List<BattingStatsDto>> getBattingGwarLeaders(
+            @RequestParam(required = false) Integer season,
+            @RequestParam(defaultValue = "10") int limit) {
+        return ResponseEntity.ok(playerApiService.getTopBattingGwar(season, limit));
+    }
+
+    @GetMapping("/leaders/gwar/pitching")
+    @Operation(summary = "Get pitching gWAR leaders", description = "Returns top pitchers by gWAR (Grove WAR) for a season")
+    public ResponseEntity<List<PitchingStatsDto>> getPitchingGwarLeaders(
+            @RequestParam(required = false) Integer season,
+            @RequestParam(defaultValue = "10") int limit) {
+        return ResponseEntity.ok(playerApiService.getTopPitchingGwar(season, limit));
+    }
+
+    @GetMapping("/leaders/oaa")
+    @Operation(summary = "Get OAA leaders", description = "Returns top fielders by Outs Above Average for a season")
+    public ResponseEntity<List<BattingStatsDto>> getOaaLeaders(
+            @RequestParam(required = false) Integer season,
+            @RequestParam(defaultValue = "10") int limit) {
+        return ResponseEntity.ok(playerApiService.getTopOaa(season, limit));
+    }
+
+    @GetMapping("/{id}/gwar-breakdown")
+    @Operation(summary = "Get gWAR breakdown", description = "Returns detailed breakdown of gWAR components for a player")
+    public ResponseEntity<GwarBreakdownDto> getGwarBreakdown(
+            @PathVariable Long id,
+            @RequestParam(required = false) Integer season) {
+        return ResponseEntity.ok(playerApiService.getGwarBreakdown(id, season));
+    }
 }

backend/src/main/java/com/mlbstats/api/dto/BattingStatsDto.java

@@ -44,7 +44,15 @@ public record BattingStatsDto(
         BigDecimal xslg,
         BigDecimal xwoba,
         BigDecimal kPct,
-        BigDecimal bbPct
+        BigDecimal bbPct,
+        // gWAR (Grove WAR) fields
+        BigDecimal gwar,
+        BigDecimal gwarBatting,
+        BigDecimal gwarBaserunning,
+        BigDecimal gwarFielding,
+        BigDecimal gwarPositional,
+        BigDecimal gwarReplacement,
+        Integer oaa
 ) {
     public static BattingStatsDto fromEntity(PlayerBattingStats stats) {
         return new BattingStatsDto(
@@ -86,7 +94,14 @@ public static BattingStatsDto fromEntity(PlayerBattingStats stats) {
                 stats.getXslg(),
                 stats.getXwoba(),
                 stats.getKPct(),
-                stats.getBbPct()
+                stats.getBbPct(),
+                stats.getGwar(),
+                stats.getGwarBatting(),
+                stats.getGwarBaserunning(),
+                stats.getGwarFielding(),
+                stats.getGwarPositional(),
+                stats.getGwarReplacement(),
+                stats.getOaa()
         );
     }
 }

backend/src/main/java/com/mlbstats/api/dto/GwarBreakdownDto.java

@@ -0,0 +1,79 @@
+package com.mlbstats.api.dto;
+
+import java.math.BigDecimal;
+
+/**
+ * DTO for displaying a detailed breakdown of gWAR components.
+ * All component values are in runs above average/replacement.
+ */
+public record GwarBreakdownDto(
+        PlayerDto player,
+        Integer season,
+        BigDecimal gwar,
+        BigDecimal officialWar,
+        // Component breakdown (in runs)
+        BigDecimal batting,
+        BigDecimal baserunning,
+        BigDecimal fielding,
+        BigDecimal positional,
+        BigDecimal replacement,
+        // Additional context
+        String position,
+        Integer oaa,
+        String methodologyUrl
+) {
+    public static final String METHODOLOGY_URL = "/docs/GWAR_METHODOLOGY.md";
+
+    public static GwarBreakdownDto forBatter(
+            PlayerDto player,
+            Integer season,
+            BigDecimal gwar,
+            BigDecimal officialWar,
+            BigDecimal batting,
+            BigDecimal baserunning,
+            BigDecimal fielding,
+            BigDecimal positional,
+            BigDecimal replacement,
+            String position,
+            Integer oaa
+    ) {
+        return new GwarBreakdownDto(
+                player,
+                season,
+                gwar,
+                officialWar,
+                batting,
+                baserunning,
+                fielding,
+                positional,
+                replacement,
+                position,
+                oaa,
+                METHODOLOGY_URL
+        );
+    }
+
+    public static GwarBreakdownDto forPitcher(
+            PlayerDto player,
+            Integer season,
+            BigDecimal gwar,
+            BigDecimal officialWar,
+            BigDecimal pitching,
+            BigDecimal replacement
+    ) {
+        return new GwarBreakdownDto(
+                player,
+                season,
+                gwar,
+                officialWar,
+                pitching,          // pitching runs stored in batting slot
+                null,              // no baserunning
+                null,              // no fielding for pitchers
+                null,              // no positional for pitchers
+                replacement,
+                "P",
+                null,
+                METHODOLOGY_URL
+        );
+    }
+}

backend/src/main/java/com/mlbstats/api/dto/PitchingStatsDto.java

@@ -44,7 +44,11 @@ public record PitchingStatsDto(
         BigDecimal xera,
         Integer avgSpinRate,
         BigDecimal whiffPct,
-        BigDecimal chasePct
+        BigDecimal chasePct,
+        // gWAR (Grove WAR) fields
+        BigDecimal gwar,
+        BigDecimal gwarPitching,
+        BigDecimal gwarReplacement
 ) {
     public static PitchingStatsDto fromEntity(PlayerPitchingStats stats) {
         return new PitchingStatsDto(
@@ -86,7 +90,10 @@ public static PitchingStatsDto fromEntity(PlayerPitchingStats stats) {
                 stats.getXera(),
                 stats.getAvgSpinRate(),
                 stats.getWhiffPct(),
-                stats.getChasePct()
+                stats.getChasePct(),
+                stats.getGwar(),
+                stats.getGwarPitching(),
+                stats.getGwarReplacement()
         );
     }
 }

backend/src/main/java/com/mlbstats/api/service/PlayerApiService.java

@@ -591,4 +591,99 @@ public List<PitchingStatsDto> getTopWhiffPct(Integer season, java.math.BigDecima
                 .map(PitchingStatsDto::fromEntity)
                 .toList();
     }
+
+    // ================================================================================
+    // gWAR (Grove WAR) Leaderboards
+    // ================================================================================
+
+    @Cacheable(value = CacheConfig.LEADERBOARDS, key = "'batting_gwar_' + #season + '_' + #limit")
+    public List<BattingStatsDto> getTopBattingGwar(Integer season, int limit) {
+        if (season == null) {
+            season = DateUtils.getCurrentSeason();
+        }
+        return battingStatsRepository.findTopGwar(season).stream()
+                .limit(limit)
+                .map(BattingStatsDto::fromEntity)
+                .toList();
+    }
+
+    @Cacheable(value = CacheConfig.LEADERBOARDS, key = "'pitching_gwar_' + #season + '_' + #limit")
+    public List<PitchingStatsDto> getTopPitchingGwar(Integer season, int limit) {
+        if (season == null) {
+            season = DateUtils.getCurrentSeason();
+        }
+        return pitchingStatsRepository.findTopGwar(season).stream()
+                .limit(limit)
+                .map(PitchingStatsDto::fromEntity)
+                .toList();
+    }
+
+    @Cacheable(value = CacheConfig.LEADERBOARDS, key = "'oaa_' + #season + '_' + #limit")
+    public List<BattingStatsDto> getTopOaa(Integer season, int limit) {
+        if (season == null) {
+            season = DateUtils.getCurrentSeason();
+        }
+        return battingStatsRepository.findTopOaa(season).stream()
+                .limit(limit)
+                .map(BattingStatsDto::fromEntity)
+                .toList();
+    }
+
+    /**
+     * Gets the gWAR breakdown for a player in a given season.
+     * <p>
+     * Note: For two-way players (e.g., Shohei Ohtani) who have both batting and pitching
+     * stats, this method returns the batting breakdown. A future enhancement could return
+     * both or use the player's primary position to determine which to prioritize.
+     */
+    public GwarBreakdownDto getGwarBreakdown(Long playerId, Integer season) {
+        if (season == null) {
+            season = DateUtils.getCurrentSeason();
+        }
+
+        Player player = playerRepository.findById(playerId)
+                .orElseThrow(() -> new ResourceNotFoundException("Player", playerId));
+
+        // Check batting stats first (for two-way players, batting is returned)
+        List<PlayerBattingStats> battingStats = battingStatsRepository.findByPlayerIdAndSeason(playerId, season);
+        if (!battingStats.isEmpty() && battingStats.get(0).getGwar() != null) {
+            PlayerBattingStats stats = battingStats.get(0);
+            return GwarBreakdownDto.forBatter(
+                    PlayerDto.fromEntity(player),
+                    season,
+                    stats.getGwar(),
+                    stats.getWar(),
+                    stats.getGwarBatting(),
+                    stats.getGwarBaserunning(),
+                    stats.getGwarFielding(),
+                    stats.getGwarPositional(),
+                    stats.getGwarReplacement(),
+                    player.getPosition(),
+                    stats.getOaa()
+            );
+        }
+
+        // Check pitching stats
+        List<PlayerPitchingStats> pitchingStats = pitchingStatsRepository.findByPlayerIdAndSeason(playerId, season);
+        if (!pitchingStats.isEmpty() && pitchingStats.get(0).getGwar() != null) {
+            PlayerPitchingStats stats = pitchingStats.get(0);
+            return GwarBreakdownDto.forPitcher(
+                    PlayerDto.fromEntity(player),
+                    season,
+                    stats.getGwar(),
+                    stats.getWar(),
+                    stats.getGwarPitching(),
+                    stats.getGwarReplacement()
+            );
+        }
+
+        // No gWAR data available
+        return GwarBreakdownDto.forBatter(
+                PlayerDto.fromEntity(player),
+                season,
+                null, null, null, null, null, null, null,
+                player.getPosition(),
+                null
+        );
+    }
 }

backend/src/main/java/com/mlbstats/common/config/RestClientConfig.java

@@ -27,4 +27,17 @@ public RestClient mlbApiRestClient() {
                 .defaultHeader("Accept", "application/json")
                 .build();
     }
+
+    @Bean
+    public RestClient baseballSavantRestClient() {
+        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
+        factory.setConnectTimeout(timeout);
+        factory.setReadTimeout(60000); // Longer timeout for CSV downloads
+
+        return RestClient.builder()
+                .requestFactory(factory)
+                .defaultHeader("Accept", "text/csv")
+                .defaultHeader("User-Agent", "MLB-Stats-App/1.0")
+                .build();
+    }
 }

backend/src/main/java/com/mlbstats/domain/constants/LeagueConstants.java

@@ -0,0 +1,66 @@
+package com.mlbstats.domain.constants;
+
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+
+/**
+ * Stores season-specific league constants used for gWAR calculations.
+ * These values change each season based on league-wide offensive environment.
+ */
+@Entity
+@Table(name = "league_constants")
+@Getter
+@Setter
+@NoArgsConstructor
+public class LeagueConstants {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false, unique = true)
+    private Integer season;
+
+    /**
+     * League average wOBA - used as baseline for wRAA calculation
+     */
+    @Column(name = "lg_woba", precision = 5, scale = 4, nullable = false)
+    private BigDecimal lgWoba;
+
+    /**
+     * wOBA scale - converts wOBA to runs above average
+     */
+    @Column(name = "woba_scale", precision = 5, scale = 4, nullable = false)
+    private BigDecimal wobaScale;
+
+    /**
+     * League average runs per plate appearance
+     */
+    @Column(name = "lg_r_per_pa", precision = 6, scale = 5, nullable = false)
+    private BigDecimal lgRPerPa;
+
+    /**
+     * FIP constant for the season (used to scale FIP to ERA)
+     */
+    @Column(name = "fip_constant", precision = 4, scale = 2, nullable = false)
+    private BigDecimal fipConstant;
+
+    /**
+     * Runs per win (typically around 10)
+     */
+    @Column(name = "runs_per_win", precision = 4, scale = 2)
+    private BigDecimal runsPerWin = new BigDecimal("10.0");
+
+    @Column(name = "created_at")
+    private LocalDateTime createdAt;
+
+    @PrePersist
+    protected void onCreate() {
+        createdAt = LocalDateTime.now();
+    }
+}

backend/src/main/java/com/mlbstats/domain/constants/LeagueConstantsRepository.java

@@ -0,0 +1,12 @@
+package com.mlbstats.domain.constants;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.Optional;
+
+@Repository
+public interface LeagueConstantsRepository extends JpaRepository<LeagueConstants, Long> {
+
+    Optional<LeagueConstants> findBySeason(Integer season);
+}