While baseball data usually focuses on player matchups, the historical record between certain teams and umpires reveals staggering disparities. Across 4,641 team-umpire pairings, historical win rates swing by more than 40 percentage points from a team's best umpire matchup to their worst.
For instance, the San Francisco Giants have won 41% more often with Jansen Visconti behind the plate than their franchise baseline, while the LA Angels' win rate plummets 43% below average when Carlos Torres calls their games. Meanwhile, Vic Carapazza historically ejected Blue Jays personnel at a rate 25.7 points above the league average. These are the kinds of edges that move prediction markets like Kalshi and Polymarket, where game-level outcomes trade in real time.
We ranked MLB umpires since 1974 on strike zone accuracy, ejection rates, and run differentials. Search your team below.
The headline numbers
- The dataset covers 4,641 umpire-team pairings across 217 umpires and all 30 MLB teams (1974-2025).
- The gap between a team's best and worst umpire pairing can exceed 40 percentage points in win probability.
Strike zone accuracy
- Rob Drake has the worst strike zone accuracy of any active umpire at 91.32%, across 1,396 games.
- John Libka leads all active umpires at 94.95% accuracy. Pat Hoberg, long considered the league's gold standard, was fired by MLB in 2024 following a gambling investigation, leaving a clear gap at the top.
Umpire-team patterns that hold over large samples
- Mark Wegner has called 56 games involving the Cincinnati Reds. Their win rate drops 27 percentage points below baseline in those games.
- D.J. Reyburn is +0.27 for the Red Sox over 26 games, but separately appeared as one of the worst umpires for the Yankees.
The most umpire-sensitive team
- The Tampa Bay Rays have the widest variance of any franchise, with a standard deviation of 0.112 across 127 umpires. Their results swing harder based on who is behind the plate than any other team in the league.
Ejections
- Vic Carapazza historically ejected Blue Jays personnel at a rate 25.7 points above the league average, the highest team-specific disparity in the dataset among umpires with 20+ games.
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How to use this before betting
Umpire assignments are posted roughly 90 minutes before first pitch. A low-rated ump in a low-total game pushes value toward the over. A high-ejection ump in a division rivalry adds variance that the market typically ignores.
Methodology: Scores pull from Umpire Scorecards (strike zone accuracy), MLB game logs (run differentials, win rates), and ejection records going back to 1979. Each umpire is scored 0 to 100. Above 75 is favorable, below 40 is a red flag. Use the active filter to focus on umpires currently working games. Data covers MLB games through the end of the 2025 regular season.
You can find the raw dataset here.
