For each team, we looked at every MLB game since 1974 and tracked what happens when a specific umpire is behind the plate. The score shows whether a team tends to win more, score more, and generally perform better or worse when that umpire is working.
100 means the team has been at its best with this umpire. 0 means the opposite. The score pulls together several signals: win rate, run differential, runs scored and allowed, close-game results, ejection patterns, and strike zone accuracy (where data is available). Each signal carries equal weight.
A red flag means two independent data sources both point the same direction: the team wins less often with this umpire, and the umpire's strike zone grades are also below average. These are the pairings worth paying attention to.
Scores based on fewer than 10 games are directional only -- treat them as a starting point, not a firm conclusion. Scores from 20 or more games carry the most weight.