E = the expected number of called strikes (found by adding up all of fitted probabilities over the pitches in the category).Using different groupings, we will divide all of the called pitches into categories. The rectangle represents the “official” strike zone, and the blue curve (the actual strike zone) is the contour line where the predicted probability of a strike is 0.5. Where p is the strike probability and s(x, y) is a smooth function of the location.īy the way, here is a picture of the fit using 2021 season data. To do this, we fit the generalized additive model We want to estimate the probability of a called strike for any pitch. The Statcast data includes the (x, y) coordinates of the pitch over the plate and the umpire call (either ball or strike) for all of the called pitches. Do the umpire errors in calling strikes vary by pitcher? In particular, are there pitchers that seem to benefit from umpire called strike errors?.Do the called strike errors vary by inning or by the top or bottom of the inning? (Here we are looking for a home field bias.).How does the count affect the number of called strike errors?.Is this really a big deal? How many strikes are gained or lost in a typical game due to the umpire errors in calling strikes?.Here are some questions that I’ll address in this post. This motivated this post where I look at the umpire errors and find some interesting biases or pattern in these errors. Recently there was an interesting Washington Post article talking about the errors umpires make in calling balls in strikes. We (that is, the players and fans) see obvious umpire mistakes on our devices and players and managers are thrown out of the game for arguing “bad” ball and strike calls. But actually this doesn’t matter since the umpire visually makes the strike/ball decision on a called pitch and teams can’t challenge that decision. In particular, we have an accurate measurement of the pitch location over the zone and one can see if a called pitch is a ball or a strike. A minor criticism is that I get tired to hearing the artificial “out” sound when a shot is outside of the lines.īaseball is similar to tennis in that the Hawkeye tracking system is currently being used in all MLB ballparks. Players can’t challenge the “in” and “out” calls and a match seems to proceed more smoothly. Actually, my first impression of the use of this tennis electronic system is favorable. All of the lines are called using the Hawkeye Line Calling System.
What is interesting about this tournament this year is that there are no line umpires. I’m currently watching the Western and Southern Open which is one of the major tennis tournaments preceding the U.S.