MLB Ump Watch
The 2025 Ump Run-Factor Board: Overs, Unders, and the Men in Blue
Published
The archive keeps score on the men keeping score. These are the 2025 rolling-window run factors for home-plate umpires from our Retrosheet mirror, anything over 1.00 leaned toward offense, anything under leaned toward pitching.
All told, 73 umpires qualify for the board, and the gap between the extremes is real: about 12 percent above the norm at the top, 14 percent below at the bottom.
Friendly skies for hitters
The friendliest zone belongs to Mark Wegner, 1.125 over 71 games calling balls and strikes, where scoring has run about 12 percent above the league norm.
Adrian Johnson is right behind at 1.101 over 89 games.
Dan Bellino is right behind at 1.097 over 96 games.
Where runs go to die
Brennan Miller runs the tightest environment in the sample, 0.863 across 73 games, where scoring has run about 14 percent below the league norm.
Close behind on the low end: David Rackley, 0.893 across 92 games.
By the numbers
The five most offense-friendly zones in the sample:
| Umpire | Run factor | Games |
|---|---|---|
| Mark Wegner | 1.125 | 71 |
| Adrian Johnson | 1.101 | 89 |
| Dan Bellino | 1.097 | 96 |
| Mike Muchlinski | 1.093 | 86 |
| Chris Guccione | 1.091 | 79 |
One more thing
These factors are built on rolling three-season windows, which is long enough to mean something and short enough to notice when a zone genuinely changes.
Think of it as weather: nobody controls it, everybody plays in it, and only some people bother to check it before first pitch.
These are historical tendencies from seasons past, not tonight's assignments, treat them as trivia about the shape of the sport, not a betting signal on any specific game.