Alan Zendell. February 24, 2025

We all need a break from worrying about whether Donald Trump can upend our Constitution and become a virtual king. Since many Americans are in mourning and withdrawn since the Super Bowl, I’m focusing on baseball today. Specifically, on the arrival of robot umpires during Spring major league games.

Baseball needs this. Not as badly as football, but neither the NCAA nor the NFL seems inclined to make such a change. Ironically, it would be easy to fix the absolute worst thing about football: spotting the ball accurately at the end of a play. How many times have you seen a game turn on a “4^th and inches” call? Referees can’t even place a football down within a couples of inches of where it should be after an incomplete pass or penalty.

At the end of a play that resembles a rugby scrum, like the fashionable Tush Push perfected by the Philadelphia Eagles, television cameras and observers in the coaches’ booths have no idea where the ball ended up, surely not within a critical couple of inches. How do we fix that? Place micro-transmitters in the ends of every football, and set up receiving antennas along both sidelines. Football is a high-profit business, so cost isn’t an issue. It’s not hard to find a transmitting frequency that’s not affected by a two-ton pile of humans.

Back to baseball. I was an umpire when my kids were growing up. I even taught umpire school, and I’d begin the course by asking: “Who can tell me what a strike is?” After a dozen or so wrong answers, I’d say: “A strike is anything the umpire says is a strike.” That sounds pretty arbitrary, because it is.

Anyone who watches baseball knows a good umpire is right more than 90% of the time, but if 250 pitches are thrown in a game, up to twenty are likely to be miscalled. Anyone who’s been an umpire knows it’s physically impossible to call every pitch accurately, especially pitches that touch one of the corners of that rectangle you see in every baseball telecast. It happens so often, baseball had to outlaw arguing over ball and strike calls. Anyone who challenges a pitch call is likely to be thrown out of the game.

Baseball players accept that umpires have their own strike zones. We frequently hear commentators say things like: “This guy has a high strike zone,” or “He’s a hitter’s umpire,” meaning his strike zone is smaller than usual, making it more difficult for the pitcher. On average, a human umpire’s strike zone averages, top to bottom, from 55.6% to 24.2% of a player’s height. The robotic Automated Ball-Strike System (ABS) always uses exactly the same strike zone, based on the precise height of the batter. The strike zone is always between 53.5% and 27.0% of the batter’s measured height. MLB provided the following chart to illustrate this:

Note that the average human-called strike zone tends to miss the four corners of the rectangle that defines the robot strike zone. That means batters will see more strikes called at the corners but fewer at the high and low extremes when robots are in full use. And scrappy players who bat from an exaggerated crouch may have to rethink that – ABS always assumes the batter is standing tall.

In 2006, I published a novel, The Portal, in which my main character was, among other things, a baseball star a hundred years in the future. I described a robot umpire in that book as “an inset metal box with identical dimensions [to home plate] that [lay] beneath it. The umpire worked by scanning a batter to create a three-dimensional strike zone as a hologram shimmering in the air. Microchips embedded in the artificial rawhide that covered the baseballs emitted cold sparks whenever they intersected the strike zone. No one argued with electronic umpires…”

I thought that was a pretty cool approach, but ABS uses a series of radars to accomplish the same thing. It’s been used in the minor leagues for a couple of years, but in 2025, robot umpires are being debuted in Spring major league games. Human umpires will call balls and strikes, but this Spring, each team gets to challenge two pitches in each game. If the ABS sides with the challenger, the team is awarded another potential challenge. Only batters, catchers, and pitchers may challenge an umpire’s call.

Robot umpires will change the game considerably. For example, human umpires vary their strike zones depending on the batter’s count and the game situation. Historical data show that on average a human umpire’s strike zone, (the rounded red shape in the figure,) ranges from 412 square inches to 550 square inches. Strike zones get smaller when a batter’s count has more strikes, larger, when it has more balls. ABS’ strike zone is always 443 square inches, much smaller than the average human strike zone, which should favor hitters.

If you’re a baseball fan, this will be a welcome added dimension to the game. But even if you’re not, isn’t this more fun than watching Donald Trump create mayhem?