MLB introduced the Automated Ball-Strike (ABS) Challenge System powered by T-Mobile beginning with the 2026 season. Only batters and pitchers/catchers may initiate a challenge. Each team starts with two challenges; teams will lose the ability to challenge after they do so incorrectly twice. The ABS zone is set as follows: the top is 53.5% of a player's measured height without cleats, the bottom is 27%, and pitch location is captured above the middle of the plate, not the front.
This page shows Statcast's advanced ABS metrics. For an at-a-glance dashboard, go here.
How to read these metrics: Challenge rate is “rate of challenges out of challengeable pitches,” defined as bad outcome non-swings with challenges remaining. (So, called balls against pitchers/catchers; called strikes against batters.) Expected challenges are based on a model that includes pitch location, number of remaining challenges, runners on, and ball/strike/out situation. [Read more here.]
Using that model, we can compare actual challenges vs. expected challenges and also actual overturns vs. expected overturns, converted into a single outcome. One of the best AAA challengers in 2025, Jamie Westbrook, won +5.4 more challenges than expected and lost -2.7 fewer than expected (when fielders challenged him), resulting in +8.1 overturns vs. expected, an excellent mark.
