Overview
- Only the batter, catcher or pitcher may initiate a head-tap challenge within roughly two seconds, and umpires can deny requests they deem late or aided from the dugout.
- MLB’s ABS zone is a two-dimensional rectangle 17 inches wide, with the top at 53.5% of a batter’s height and the bottom at 27%, verified by independent height measurements in camp.
- Clubs start with two challenges and regain at least one per extra inning if they have none left; the system is turned off when a position player pitches.
- If an ABS review and a traditional replay are requested on the same sequence, the ball-strike ruling is decided first, and umpires retain discretion to place runners after overturned calls.
- League testing showed about four challenges per game with roughly 50–52% overturned, catchers had the highest success rates, managers are crafting usage plans, and Braves left-hander Chris Sale says he will not use challenges.