The Minors utilized this process for the 2024 season. I watch a bunch of MiLB games this year and thought it worked well. Didn’t add lenthy delays to get the decision, was done within 5seconds.
While MLB initially seemed to embrace a fully robotic zone, they’ve pivoted to the challenge system after testing both the challenge and the full ABS in the minors.
The challenge system leaves the human umpire as the default. Each team gets a finite number of challenges to turn to the automatic zone on borderline pitches. Challenges must be called for in real time by the hitter, pitcher or catcher. That’ll leave some missed calls but reduces the likelihood of a blown call on an especially important pitch.
That assuages some concerns about the rule book strike zone not perfectly aligning with the way players expect the game to be called. One common complaint about the automatic zone is its tendency to reward pitchers for clipping the top of the zone with an elevated breaking ball. That’s less likely to be an issue with the challenge system, as pitchers and catchers won’t often dispute pitches they don’t perceive as strikes themselves.