In baseball, a strikeout occurs when a pitcher throws three strikes to a batter during his time at bat. Under Rules 6.05 and 6.09 of the Official Rules of Major League Baseball, a batter becomes a runner when a third strike is not caught by the catcher with no runner on first base or when there are two outs. The strikeout is recorded, but the batter-runner must be tagged or forced out in order for the defensive team to register the out. Thus, it is possible for a pitcher to record more than three strikeouts in an inning. As a result of this rule, 93 different pitchers have struck out four batters in a half-inning of a Major League Baseball (MLB) game, the most recent being Michael Rucker of the Chicago Cubs on April 30, 2022. Four players — Chuck Finley, A. J. Burnett, Zack Greinke, and Cr