Challenge

On September 30, 2026, in the bottom of the 10th inning of a Wild Card game in Atlanta, an umpire called a 99-mph fastball a ball. Phillies catcher J.T. Realmuto tapped his helmet. Seconds later the call was reversed, strike three, and for the first time a postseason game had ended on a challenge. That moment capped the rookie season of the Automated Ball-Strike Challenge System, the newest chapter in baseball's long argument over who judges the pitch. For the first time in the major leagues, a batter, pitcher, or catcher could dispute an umpire's call and have a tracking system settle it in seconds. Challenge tells the story of that season: the testing in the minor leagues, Opening Day, the catchers who mastered the system and the hitters who gambled on it, the umpires whose misses now played on the scoreboard, and the managers who could only watch. It follows the challenge into October and weighs what the numbers show. Players made 10,557 challenges in the regular season and won 54 percent. Catchers won 59 percent; pitchers, 40. The book's argument is that ABS did not change how baseball is played. It changed who judges it. In the 1870s, a batter could call for a high ball or a low ball. Baseball took that voice away in 1887. In 2026, it gave a small part of it back. The fourth book in the First Inning Baseball series, Challenge is an accessible, carefully sourced account for any fan who has ever shouted at an umpire.