The Automated Ball Strike Challenge
The human umpire still calls the pitch, and each team gets a small number of challenges on the zone.
What it actually is. The automated ball strike system tracks the pitch and defines the zone as a percentage of the hitter's height rather than by his stance. In the challenge version being used in testing, the umpire calls the pitch as normal and the pitcher, catcher or hitter may immediately challenge by tapping his helmet or cap. Teams get a small number of challenges and keep them when they are right.
What somebody who knows the game gets out of it. The challenge version was chosen over full automation for a reason worth understanding: full automation removes framing entirely, which erases a real skill worth several wins a season and changes what a catcher is for. The challenge version keeps the human zone as the default and corrects only the calls somebody was confident enough to contest, which preserves framing while removing the worst misses. It is a deliberate compromise rather than a stepping stone.
The numbers worth knowing. Typically two or three challenges per team per game, retained when successful. Resolution takes a few seconds since the tracking is already live.
What people get wrong about it. The automated zone is defined by the hitter's height, so it is a different shape from the zone umpires actually call, which is an oval that is generous at the sides and tight at the top. Full automation would therefore change which pitches are strikes, not merely make the same calls more accurately.
At Little League and travel ball. None of this exists at youth level and the practical lesson is the opposite one: the zone tonight is whatever this umpire is calling, and the team that recognizes it in the first inning has an advantage for the rest of the game.
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