ABS Challenges

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.]
• A "reasonable" challenge opportunity occurs when at least one of the following is true: The original call was incorrect; the pitch is within 3 inches of the strike zone edge and an overturn would gain at least 0.3 runs; the pitch carries an expected challenge rate of at least 20%.
• A fuller explanation of these metrics can be found 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.