MLB Debuts Pitch Challenge System, Adding Replay Reviews to Strike Zone

Major League Baseball has introduced the Automated Ball-Strike (ABS) Challenge System for the 2026 season, giving games a replay-like mechanism for the most debated call in the sport: balls and strikes.

Under the new framework, home-plate umpires will still make the initial ruling, but a pitcher, catcher, or hitter can immediately challenge a call, triggering an automated review powered by Hawk-Eye tracking. The system has already been added to spring training games

High-Tech Replay System

The technology relies on 12 Hawk-Eye cameras installed around each ballpark to track pitch location in real time. When a challenge is initiated, the system compares the pitch to the batter’s individualized strike zone and delivers a near-instant decision that is shown on video boards and broadcast graphics.

MLB says the process is designed to be quick and minimally disruptive, effectively functioning as a fast “micro-replay” for the zone.

League officials have emphasized that the strike zone will be tailored to each hitter using standardized measurements, with the zone’s vertical limits determined by a percentage of the player’s height.

That individualized zone is expected to become a new skill point for players — and a new point of scrutiny for fans — as teams decide when to spend a challenge in a key count.

The bottom line is that ABS challenges won’t eliminate judgment from the sport, but just relocate it. Managers, catchers, and pitchers will be making higher-stakes decisions about which borderline calls to contest, and bettors will need to account for that new layer of strategy when pricing live lines and player props.

Effects on Sports Betting

For MLB betting, the biggest impact is likely to show up at the margins — but the margins matter. A flipped 3-1 to 2-2 call, or a reversed strike three, can materially change plate-appearance outcomes, pitch counts, bullpen timing, and ultimately totals and MLB live betting markets.

Bettors who focus on live wagering may see added volatility around leverage counts, while those betting pitcher props (strikeouts, outs recorded, walks) could find that challenge usage becomes a meaningful in-game indicator: some teams may be more aggressive in protecting pitchers on borderline edges, while others may save challenges for late innings.

Pitch Pace Rules Remain

The ABS system arrives with several 2024 pace-and-pitching rules remain part of the game. The most prominent is the pitch timer reduction with runners on base: pitchers have 18 seconds with runners aboard (down from 20), while it stays 15 seconds with the bases empty.

Pitchers still get two disengagements (step-offs or pickoff attempts) per plate appearance before risking a balk-like penalty.

MLB also kept in place additional 2024 pace-related pitching provisions, including tighter administration around pitching changes during inning breaks and a reduction in mound visit allotments. And a notable tweak: if a pitcher warms up to start an inning, he must face at least one batter (barring injury), reinforcing roster and matchup decisions.

For more information on spring training, MLB World Series betting, and the upcoming season, click here.