How Much Do Umpires Matter in Baseball Handicapping?

The following post explores the question: how much do umpires matter in baseball handicapping?

We’ve all seen it happen. Umpires can single-handedly influence the outcome of a game. Their tendencies towards strike zones and game management quickly change game dynamics.

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There are so many different factors to consider when handicapping a baseball game. Umpires are just one of those many factors. So, how much weight should we put on umpire assignments?

Here’s what you need to know.

Overview

Umpires are human beings. That means umpires are subject to psychological biases, such as home favoritism or unresolved animosity towards certain players or teams. Likewise, some umps have a wider strike zone than others.

In addition to individual tendencies and psychological biases, umpires may adjust their calls for practical reasons – like speeding up the game on get-away days, double headers, and bad weather days.

Analysis

So, how much do umpires matter when betting on baseball?

The following screenshots (source: EV Analytics) display the lowest and highest ERAs for each umpire in MLB when they’re behind the plate calling balls and strikes.

In analyzing umpire-specific ERAs, we observe a range from 4.37 with Alfonso Marquez, considered an ‘extremely hitter-friendly’ umpire, to 4.06 with Bill Miller, an ‘extremely pitcher-friendly’ umpire. These figures represent the extremes among over 120 umpires, with all other ERAs falling between these two points.

The variability between the highest and lowest umpire ERAs is 0.31 (less than 1/3 of 1 run).

While a differential of 0.31 matters to some degree, it actually indicates that the overall impact of umpires is relatively minor. The data suggest that while some umpires might slightly favor hitters or pitchers, the effect is not substantial enough to be a primary consideration for bettors.

For instance, consider two starting pitchers—one with a 2.89 ERA and the other with a 4.66 ERA. The variability between these ERAs is much greater compared to umpire influences, suggesting that bettors should prioritize pitcher matchups over umpire assignments when handicapping baseball.

Lowest MLB Umpire ERAs (6/22/2024) – Source EV Analytics

Highest MLB Umpire ERAs (6/22/2024) – Source EV Analytics

Conclusion

In conclusion, while umpires are an important factor to consider when handicapping baseball, you shouldn’t put too much weight on umpire assignments. They’re just one of many things to consider, along with other important factors like team performance and player matchups.