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%.
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.
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"Challenge Confidence Required" refers to the confidence a player needs to have
that the call will be overturned when making the challenge to make it worthwhile, given
the game situation.
