Some umpires call strikeouts with such gusto, you'd swear they like doing nothing better. But a study from two doctoral students at the Graduate School of Business shows that, in general, the men in blue are actually biased against calling a fateful third strike.
Looking at more than 1 million Major League pitches, Etan Green and David P. Daniels show just how much stingier umpires grow with the strike zone as the count goes in the pitcher's favor. Once a batter has two strikes, the probability of a called third strike drops by as much as 19 percentage points on the corners of the strike zone.
Conversely, in a three-ball count, umpires become more forgiving with the pitcher. Green says the findings show a reluctance to make a pivotal call—one resulting in an out or a walk—unless they're absolutely confident they're right. Instead they go for the less consequential alternative.
All 75 umpires in the study—which won second place at this year's MIT Sloan Sports Analytics Conference—fit the pattern. In baseball, the bias is consistently applied, making it debatable whether it's a problem, Green says. But similar tendencies may exist in "real world" arbitrations, where they'd be more troubling. "If a judge lets off a guilty offender, or a doctor makes the wrong diagnosis because he or she is erring on the side of not doing something consequential—those effects don't get recalibrated."
