Saturday, October 23, 2021

RoboUmp's Odd Strike Zone Gets AFL Game Called Early

Teams ran out of pitchers leading to a game getting called early as the 2021 Arizona Fall League's electronic umpire experiment proved problematic during Saturday's Solar Sox vs Rafters game at Salt River Fields at Talking Stick. RoboUmp's demi-sized strike zone helped produce 22 walks as Mesa and Salt River bled through 12 pitchers before the teams and umpires agreed to call off the game in the 8th inning with Salt River leading, 15-7. The Automated Ball-Strike System (ABS) is only in use for games played at Salt River Fields.

According to Keith Law at The Athletic, several rule changes were in use during the game, including a variable pitch clock, ban on shifts, and of course an automated strike zone that rendered HP Umpire Alex McKay little more than a computer mouthpiece. (If you're wondering what happens to the MiLB call-ups during the offseason, you can find some working the Arizona Fall League; McKay's crew included 1B Umpire Malachi Moore, 2B Umpire Ryan Wills, and 3B Umpire Kyle McCrady).

Returns from the game indicate an issue that has plagued electronic zones since their very inception: an unforgiving, and in this case small, strike zone that continues to fall short of the standard to which human umpires call balls and strikes. The Atlantic League version, for instance, occasionally fell prey to the opposite problem: strike zones that were too large.

For this reason, our postseason plate performance scores continue to be given in a three-metric format: UEFL f/x with a roughly one-inch margin of error nestled between the larger buffer of Zone Evaluation Equivalent and the zero-error model the viewing audience sees known as ML Public (although our version of ML Public features postgame processing data point correction whereas what fans see on TV is raw and uncorrected).


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