Is Brian O'Nora a hitter's or pitcher's umpire?

With Brian O'Nora behind the plate, MLB games average 8.74 total runs versus a league average of 9.02, a run factor of 1.01. That makes him a roughly neutral umpire.

How is an umpire's run factor measured?

From 81 games with Brian O'Nora behind the plate in our database, rebuilt nightly. A run factor of 1.00 is league average; above means more scoring in his games, below means less.

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MLB · Umpire Tendencies

Brian O'Nora

With Brian O'Nora behind the plate, MLB games average 8.74 total runs versus a league average of 9.02. That is a run factor of 1.01, #37 of 96 umpires for scoring, making him a roughly neutral umpire.

Run factor

1.01

+1%

runs vs average

Strikeout factor

0.98

-2%

strikeouts vs average

Games

behind the plate, in our data

A strikeout factor of 0.98 (-2%) reflects how wide or tight Brian O'Nora calls the zone. A wider zone means more called strikes, more strikeouts, and fewer baserunners, which is why umpire run and strikeout factors usually move together. The home team wins 56.8% of his games, close to the league's modest home rate.

How we counted

From 81 games with Brian O'Nora as home-plate umpire, rebuilt nightly. Factors are normalized so 1.00 equals the league-average umpire. A single umpire is a small slice of the season, so read the extremes as tendencies, not certainties. Descriptive, not a prediction.

Last recomputed August 23, 2026.

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