After analyzing more than 700,000 pitches thrown during the 2008 and 2009 seasons, we found that umpires frequently made errors behind the plate — about 14 percent of non-swinging pitches were called erroneously.Robots! Now!
Some of those errors occurred in fairly predictable ways. We found, for example, that umpires tended to favor the home team by expanding the strike zone, calling a strike when the pitch was actually a ball 13.3 percent of the time for home team pitchers versus 12.7 percent of the time for visitors.
Other errors were more surprising. Contrary to the expectation (or hope) that umpires would be more accurate in important situations, we found that they were, in fact, more likely to make mistakes when the game was on the line. For example, our analyses suggest that umpires were 13 percent more likely to miss an actual strike in the bottom of the ninth inning of a tie game than in the top of the first inning, on the first pitch.
We also found that the pitch count had an influence over the umpire's perception of a pitch. When the count was 3-0, and another ball would end the at-bat, the umpires mistakenly called a strike 18.6 percent of the time, compared with a 14.7 percent error rate when the count was 0-0. But when the count was 0-2, with another strike yielding a strikeout, the umpires expanded the strike zone only 7.3 percent of the time, half the error rate for 0-0. The umpires, in other words, appeared biased against ending an at-bat. ...
Baseball insiders have long suspected what our research confirms: that umpires tend to make errors in ways that favor players who have established themselves at the top of the game's status hierarchy. ...
Technologically, Major League Baseball is in a position, thanks to its high-speed camera system, to enforce a completely accurate, uniform strike zone. The question is whether we, as fans, want our games to be fair and just, or whether we are compelled to watch the game because it mimics the real world, warts and all.
March 30, 2014
Umpires Call 1 Out Of Every 7 Non-Swinging Pitches Incorrectly
Brayden King, New York Times: