How Robot Umps, ABS Impacted Ejections and Potential Rule Changes Addressed by MLB Insider

The first year of the ABS challenge system had a profound impact on the number of ejections on calls related to balls and strikes.

Per The Athletic's Will Sammon and Ken Rosenthal, MLB data revealed there was a 90 percent drop in ejections for calls on balls and strikes from 2025 to 2026.

The overall number of ejections decreased by 30 percent last season compared to 2025.

However, the report also notes MLB could give "more serious" consideration to implementing a check-swing challenge system in part because there was a 65 percent year-over-year increase for ejections on check-swing calls.

There was also an 89 percent increase from 2025 to 2026 on ejections related to replay decisions.

Just among managers, Tony Vitello of the San Francisco Giants (seven) and Aaron Boone of the New York Yankees (five) led their respective league in ejections.

MLB first introduced check-swing replay during the Arizona Fall League in 2024. It uses the same Hawk-Eye technology as the ABS system, so every stadium is already set up for it.

The check-swing replay system has gone on to be used in the minors with 2026 marking its first season at Triple-A.

Calls for check-swing replay really picked up in Game 2 of the World Series when Yandy Díaz struck out to secure a 5-4 win for the Milwaukee Brewers after the first-base umpire ruled he went around on a very close call.

There is no exact specification in the MLB rulebook for what constitutes a checked swing. A memo to teams in March outlining the replay system said a swing is "considered to have occurred if the maximum angle between the bat head and the bat handle exceeds 45 degrees."

The check-swing replay rules in the minors are similar to the ABS system. Each team starts with two challenges and a third is granted for the ninth inning if the first two are used before then.

Pitchers, hitters and catchers are the only players allowed to ask for a replay review.