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
Mark Wegner owns the most hitter-friendly environment in the sample: a 1.125 run factor across 71 games behind the plate, where scoring has run about 12 percent above the league norm.
Adrian Johnson (1.101 in 89 games) keeps the trend company.
Dan Bellino (1.097 in 96 games) keeps the trend company.
Where runs go to die
The stingiest zone belongs to Brennan Miller: 0.863 over 73 games behind the plate, where scoring has run about 14 percent below the league norm.
David Rackley is nearly as stingy at 0.893 over 92 games.
At a glance
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 |
The fine print
Because every factor rides a rolling three-season window, the board moves slowly and honestly: no single series, however strange, can rewrite it.
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.