MLB unveils ABS challenge system guidelines for 2026 season

SCOTTSDALE – Major League Baseball finalized the rules for the first year of the automated ball-strike (ABS) challenge system, which will debut on Opening Day this season. Among the latest changes, teams will always have at least one challenge in the extra innings, even if they have used their two allotted challenges within the first nine innings.

The league announced its final rules and guidelines during Cactus League Media Day on Thursday, about a week before spring training games begin.

Highlights of the new system:

• If a team enters the extra innings without any challenge, they will be given one extra innings in each innings. Challenges will not accumulate if not used. Teams will have no more than one challenge per extra inning unless they enter the extra frame with their original two intact.

• Umpires will be given discretion over plays on base, even if the pitch is being challenged. For example, the outcome of a stolen base attempt is likely to make no difference to the outcome of the challenge, with the only exception coming on a ball-four or strike-three call that is overturned. If the umpire feels that “player conduct” has affected—for example, if the catcher stops playing because he hears the fourth ball and the call is overturned—he may send the runner back to his original base and the stolen base will not count.

• If a position player is pitching, the pitch cannot be challenged.

• The league is measuring each player’s standing height to determine their individual strike zone, which will be slightly smaller than the zone called by the umpire.

• It is possible to have both an ABS challenge and a video replay challenge on the same play. If this occurs, the decision will be made on a ball-strike call first, followed by video replay on the bases.

Also on Thursday, the league announced a change to its obstruction rule: A runner who initiates contact with a fielder with the intention of drawing an obstruction call will be called out. This sometimes occurs in rundowns when a baserunner intentionally runs into a fielder in hopes of being declared safe due to an obstruction. Umpires have now been told to ignore such attempts and instead call the runner out.

Additionally, the owners voted to implement a rule requiring the base coaches to remain in their respective boxes until the pitch is delivered.