Over the past few years, Major League Baseball has been testing and modifying an automatic strike zone (ABS) that includes a challenge system. The ABS system, which has been used in Triple-A full time since 2023, was tested out during MLB Spring Training this year, and now will be fully implemented during the 2026 regular and postseason.
Umpires will continue to call balls and strikes behind home plate, but pitchers, batters, or catchers can challenge a pitch by tapping their helmet. The ABS system then quickly reviews the pitch, displays a graphic for both in-stadium and TV audiences, and issues the correct call.