MLB Ump Watch
The 2025 Ump Run-Factor Board: Overs, Unders, and the Men in Blue
Published
Some zones are cathedrals and some are closets, and the hitters know which is which long before the numbers do. Our Retrosheet build keeps score anyway: 2025 rolling run factors per home-plate umpire, with 1.00 meaning perfectly neutral.
There are 73 qualified names in the sample, spanning about 12 percent above average down to 14 percent below, a wider spread than most fans would guess.
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 (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 over-leaning end of the board, in one look:
| 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 |
Worth remembering
Method matters here: each factor is a rolling three-season sample, so one wild week cannot vault a name to the top of the board, and a single quiet month cannot bury one.
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.