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MLB robot umpires, explained: What to know about baseball's ABS challenge system and how it will be used in 2026

It's official: MLB will be using the ABS challenge system throughout the entire 2026 season.

Robot umpires — also called "automated balls and strikes" (ABS) — have been used in the minor leagues and during the 2025 MLB All-Star Game, and now the system will come into full effect in the major leagues. While human plate empires will call balls and strikes, teams can challenge two calls per game and get additional appeals in extra innings.

The challenge system will be used for all spring training, regular season and postseason games beginning in 2026. Here's what to know about ABS before it becomes a MLB mainstay.

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