• Yamamoto's lines and every appearance. MLB Stats API (MLB Advanced Media), statsapi.mlb.com/api/v1, fetched : people/808967/stats (yearByYear and career, gameType R and P), the postseason gameLog for each season, the Dodgers' postseason schedule (series, game numbers, final scores, decisions), and the live feed (api/v1.1/game/{gamePk}/feed/live) of every game he pitched, for the batters, last pitches, and the runners charged to him.
• Every postseason since 1903. MLB Stats API, fetched : stats?stats=season&group=pitching&gameType=P for each season (every pitcher's postseason line), teams/stats (team postseason totals) and the schedule with decisions, one call per season.
• Pitches. Baseball Savant (MLB Advanced Media), Statcast Search CSV, one season and game type per call, e.g. 2025 postseason, and the Pitch Arsenal Stats leaderboard (used only to check the whiff arithmetic), fetched .
• World Series MVP and the three-win, Game 6 and Game 7 history. Anthony Castrovince, “Yoshinobu Yamamoto wins 2025 World Series MVP,” MLB.com, 2 Nov 2025, mlb.com/news/yoshinobu-yamamoto-wins-2025-world-series-mvp (read 8 Oct 2026). The article's counts (the 14th pitcher with three wins in one World Series; the fourth to win both Game 6 and Game 7) are recomputed from the schedule data on every build, and the build fails if they disagree.
• Checked against Baseball-Reference (read 8 Oct 2026): the postseason tables on the player pages for Yoshinobu Yamamoto, Christy Mathewson, Orel Hershiser, Burt Hooton, Madison Bumgarner, Mariano Rivera and Clayton Kershaw. See the checks below.
• Photo. All-Pro Reels (Joe Glorioso, for Washington Times Sports), “Dodgers at Nationals,” Nationals Park, April 2024, via Wikimedia Commons, File:Yoshinobu Yamamoto in 2024 (53676737736) (cropped).jpg, licensed CC BY-SA 2.0; cropped on Commons and resized here, under the same license. It is the photo on his Wikipedia article (accessed 8 Oct 2026).

How the numbers are built