MLB Ump Watch
Ump Watch: The 2025 Run-Environment Board
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
Top of the board sits Mark Wegner at 1.125 across 71 games, 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.
The pitchers' best friends
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.
David Rackley (0.893 in 92 games) rounds out the pitching-friendly wing.
By the numbers
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.