ABS Challenge
MLB's 2026 rule allowing teams to challenge ball/strike calls using a computerized strike zone. Each team gets 2 challenges per game and retains a challenge if the review reverses the call.
Example Usage
“The count was 3-2 and the pitcher had worked all game with that low pitch, the catcher threw the challenge flag and the ABS reversed it to strike three.”
ABS Challenge
The ABS Challenge (Automated Ball-Strike Challenge) is an MLB rule introduced in 2026 that allows teams to challenge ball-and-strike calls using a computerized strike zone system. It represents a significant shift in how baseball adjudicates pitch location disputes.
How It Works
Each team receives 2 challenges per game. When a manager, catcher, or batter disagrees with a ball or strike call:
- The challenging team signals the challenge (typically through a designated gesture or flag)
- The call is reviewed against the ABS (Automated Ball-Strike) system, a computer-vision tracking system that measures pitch location relative to the official strike zone
- If the ABS reverses the call, the challenging team retains their challenge
- If the ABS upholds the umpire's call, the challenging team loses the challenge
Unused challenges do not carry over between innings or games.
What the ABS System Measures
The ABS uses the same tracking technology as Statcast. The strike zone is defined per batter, it adjusts to each hitter's actual measured strike zone (the region between the knees and the midpoint of the torso, over the width of home plate).
Pitches that catch any part of the plate and zone are ruled strikes. Pitches entirely outside are balls.
Strategic Implications
The challenge system adds a new layer of strategic decision-making:
- Catchers and batters must decide quickly whether a borderline call is worth challenging
- Managers may hold challenges for critical late-game at-bats rather than use them early
- Pitchers who work the edges need to understand that close calls can now be reviewed
- Challenge timing in two-strike or three-ball counts becomes particularly important
Why It Matters for Coaches
Even at levels where ABS is not implemented, the challenge system reflects a broader shift in how strike zones are understood and enforced. Teaching pitchers to attack the zone with precision, not just nibble at the corners hoping for a generous call, becomes more important when close pitches are subject to objective review.
Related Terms
Pitcher's Count
A count with more strikes than balls, 0-2 or 1-2, where the pitcher can work off the plate, throw breaking balls in the dirt, and make the hitter protect against pitches they normally would not swing at.
Hitter's Count
A count with more balls than strikes, 2-0, 3-0, 3-1, where the pitcher needs to throw a strike and the hitter can look for their pitch and be selective about what they swing at.
Plate Discipline
A hitter's ability to identify balls vs. strikes and make smart swing decisions. Measured through walk rate, strikeout rate, and chase rate. Plate discipline is one of the highest-value skills a hitter can develop.
Walk Rate
The percentage of plate appearances that result in a base on balls. A key plate discipline indicator, hitters who walk frequently show strong pitch recognition and zone management.
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