Lefty-righty switch

In baseball, the lefty-righty switch is a maneuver by which a player who may be at a disadvantage against an opponent of a certain handedness is replaced by a substitute who is better suited for the situation.

For example, with a left-handed batter due to hit at a critical point in a game, a right-handed pitcher may be replaced by a left-handed relief pitcher, as pitchers generally fare better when pitching from the same side that a batter hits from. Similarly, with a left-handed pitcher in the game, teams may replace a left-handed batter with a right-handed pinch hitter, as batters generally fare better when hitting from the opposite side that a pitcher throws from.