The incompetent employee who schmoozes his or her way to a promotion is a cliche of corporate life. You can’t schmooze your way into Major League Baseball. But players who spend more time around umpires do seem to enjoy better treatment when up at bat.
This is the conclusion of Dr. Brian Mills of the University of Florida in a recent paper “Social Pressure at the Plate.” Writing in Managerial and Decision Economics, he notes the “theory of mere exposure” - that repeated, positive contact can bias a manager in favor of an employee. As an expert in sports economics, he is interested in how catchers provide a perfect case study for the phenomenon.
In baseball, catchers spend half the game near the home plate umpire and often engage in conversation. Mills quotes one catcher who says, “Usually I like to keep it as a running conversation [with the umpire] throughout the day.” But when catchers go up to bat, the league expects umpires to call strikes and balls objectively. Mills investigated umpires’ treatment of batting catchers to test umpires’ ability to remain unbiased.
Baseball has the technology to track pitches and determine where they crossed the plate relative to a standard strike zone. It’s used to inform viewers, but in the interest of not losing the “human element” of baseball, umpires make the calls while machines track their performance.
Mills took pitch location data from the 2007-2010 Major League Baseball seasons and narrowed it down to 1.2 million pitches in which the home plate umpire had to make a non-obvious call. The data also included information to be used as controls, such as the count (current number of balls versus strikes), type of pitch, which team was home, and team quality as measured by number of wins. Since the height and stance of the batter determines the vertical limits of the strike zone, Mills also defined a dynamic estimate of the strike zone for batters based on the full data set.
By comparing the odds of a strike being called against catchers and non-catchers, the study found that the umpires did favor catchers: The probability of a strike was 0.74% lower for catchers, whose strike zone was “about 9.8-12.6 square inches smaller.” The effect was strongest on the inside of the strike zone, suggesting that umpires punished pitchers for throwing inside pitches that could hit the catcher.
So the umpire is biased. But does a bias of under one percentage point matter? Mills draws on other research to note that “On average, changing a ball to a strike call impacts the expected runs scored by 0.15 runs per pitch” and that the pro-catcher bias accounts for a 2% increase in the number of runs attributed to a selected sample of catchers. The impact is small but non-trivial. Mills points out, however, that the effect does not significantly affect game outcomes as each team’s catcher benefits from the same bias.
Other workplace biases, however, seemed to have a stronger influence on umpires’ calls.
According to a bias called “inequality aversion,” managers tend to downplay differences in employee performance in favor of egalitarianism. In the same way, umpires tend to favor the underdog in any given pitch count, “with the size of the strike zone decreasing by as much as 26 percent from the most extreme batter’s count (three balls and zero strikes) to the most extreme pitcher’s count (zero balls and two strikes).”
A bias to view and treat high-status individuals better also pervades the baseball diamond just as much as the workplace. Older players and players who rank highly on a sabermetric for total value called Wins Above Replacement receive better odds of a ball when up at bat.
The fact that biases affect umpires won’t surprise passionate fans that see it at work (imagined or real) every week. But the MLB tracks the accuracy of umpire decisions, which in turns impacts their careers. Dr. Mills believes this should serve as a lesson to workplaces everywhere. If umpires struggle to stay objective in such a stark and monitored environment, then managers in fields where performance is much more difficult to judge (and no one boos when you get a call wrong) will have to work even harder to stay unbiased.