{"sport":"mlb","slug":"walter-hackett","bio":{"fullName":"Walter Hackett","position":"SS","team":"ATL","heightInches":0,"weightLbs":0,"birthDate":"1857-08-15","rookieSeason":1884,"lastSeason":1885,"status":"RET","externalIds":{"mlbam":"115288","chadwick":"84d961b9","retro":"hackw101","wikidata":"Q7965045"}},"draft":null,"statTables":[{"id":"batting","label":"Batting","columns":[{"key":"g"},{"key":"ab"},{"key":"r"},{"key":"h"},{"key":"doubles"},{"key":"triples"},{"key":"hr"},{"key":"rbi"},{"key":"sb"},{"key":"bb"},{"key":"so"},{"key":"avg"},{"key":"obp"},{"key":"slg"},{"key":"ops"}],"rows":[{"season":1884,"seasonType":"REG","team":"Boston Unions","gamesPlayed":103,"values":{"g":103,"ab":415,"r":71,"h":101,"doubles":19,"triples":0,"hr":1,"rbi":null,"sb":null,"bb":7,"so":null,"avg":0.243,"obp":null,"slg":0.296,"ops":null},"rowScope":"team"},{"season":1885,"seasonType":"REG","team":"ATL","gamesPlayed":35,"values":{"g":35,"ab":125,"r":8,"h":23,"doubles":3,"triples":0,"hr":0,"rbi":9,"sb":null,"bb":3,"so":22,"avg":0.184,"obp":null,"slg":0.208,"ops":null},"rowScope":"team"}],"careerTotals":{"REG":{"g":138,"ab":540,"r":79,"h":124,"doubles":22,"triples":0,"hr":1,"rbi":9,"sb":null,"bb":10,"so":22,"avg":0.23,"obp":null,"slg":0.276,"ops":null}}},{"id":"advanced","label":"Advanced (League-Relative)","columns":[{"key":"ops_plus","label":"OPS+","description":"On-base plus slugging vs the player's own season+league (100 = league average). Park-unadjusted; OBP uses a consistent (H+BB)/(AB+BB) rate. Higher is better.","format":"int","higherIsBetter":true},{"key":"era_plus","label":"ERA+","description":"Earned-run average vs the player's own season+league (100 = league average). Park-unadjusted. Higher is better.","format":"int","higherIsBetter":true}],"rows":[{"season":1884,"seasonType":"REG","team":"Boston Unions","values":{"ops_plus":93,"era_plus":null},"rowScope":"team"},{"season":1885,"seasonType":"REG","team":"ATL","values":{"ops_plus":36,"era_plus":null},"rowScope":"team"}],"careerTotals":{"REG":{"ops_plus":79,"era_plus":null}},"advancedMeta":{"method":"computed in-house from MLB StatsAPI season batting/pitching lines, normalized to each player's own (season, league) baseline","formulas":{"era_plus":"100 * lgERA / playerERA (league ERA = 9 * ΣER / ΣIP over the season+league)","ops_plus":"100 * (OBP/lgOBP + SLG/lgSLG - 1)","career_era_plus":"innings-weighted league ERA / career ERA (B-Ref method)","career_ops_plus":"AB-weighted OBP & SLG against AB-weighted league rates"},"caveats":["PARK-UNADJUSTED: no park-factor data exists in the corpus, so these are league-relative but not park-adjusted (true B-Ref ERA+/OPS+ also divide by a park factor)","OBP baseline uses a consistent (H+BB)/(AB+BB) reached-base rate for BOTH player and league — the source feed carries no HBP or SF, so this is not the full (H+BB+HBP)/(AB+BB+HBP+SF) OBP; SLG is exact from the hit-type columns","league resolved from team code + season (most-recently-founded franchise existing by that season); the same resolver builds the baseline and looks up the player, so ratios stay internally coherent","a (season, league) bucket below the sample floor (3000 AB batting / 1000 IP pitching) yields null — no noisy baselines","regular season only; postseason lines are excluded from league baselines and metrics","AL and NL and each historical/Negro league are normalized separately — never blended across leagues or eras"]}}],"dataSources":["MLB StatsAPI (statsapi.mlb.com — official public league API; facts only, raw payloads not republished)"],"generatedAt":"2026-07-03T08:11:48.216Z"}