How does ABS work? What automated ball-strike rule means for MLB

Key Points:

• Major League Baseball has introduced an automated ball-strike (ABS) challenge system starting with the 2026 season opener, allowing players to challenge ball and strike calls by tapping their helmet or hat immediately after a pitch.
• Each team begins with two challenges per game, retaining the ability to continue challenging if successful, but losing all challenges after two unsuccessful attempts, with the pitch replayed via real-time animation on stadium videoboards and broadcasts.
• Spring training data showed a 53% overall success rate for challenges, with defense-initiated challenges succeeding 60% of the time compared to 45% for hitters, highlighting the complexity and strategic nature of when to use challenges.
• Teams are particularly focused on calls at the top of the strike zone, which umpires tend to miss more frequently, and have measured players' heights carefully to calibrate the zone, though stance is not factored into zone height.
• Strategies vary on whether pitchers should be allowed to challenge calls, with many teams preferring catchers to handle challenges due to pitchers' limited ability to judge pitch location immediately after throwing and emotional investment; teams also emphasize using challenges selectively in high-leverage situations.