Reliever

In baseball and softball, a relief pitcher or reliever is a pitcher who enters the game after the starting pitcher is removed due to injury, ineffectiveness, fatigue, ejection, or for other strategic reasons, such as being substituted by a pinch hitter. Relief pitchers are further divided informally into various roles, such as closers, set-up relief pitchers, middle relief pitchers, left/right-handed specialists, and long relievers. Whereas starting pitchers usually rest several days before pitching in a game again due to the number of pitches thrown, relief pitchers are expected to be more flexible and typically pitch more games but with fewer innings pitched. A team's staff of relievers is normally referred to metonymically as a team's bullpen, which refers to the area where the relievers sit during games, and where they warm-up prior to entering the game.

In the early days of Major League Baseball (MLB), substituting a player was not allowed except for sickness or injury. An ineffective pitcher would switch positions with another player on the field. The first relief appearance in the major leagues was in 1876 with Boston Red Caps outfielder Jack Manning switching positions with pitcher Joe Borden. In this early era, relief pitchers changing from a position role to the pitcher's box in this way were often called "change" pitchers. This strategy of switching players between the mound and the outfield is still occasionally employed in modern baseball, sometimes in long extra inning games where a team is running out of players. In 1889, the first bullpen appearance occurred after rules were changed to allow a player substitution at any time. Early relief pitchers were normally starting pitchers pitching one or two innings in between starts. In 1903, during the second game of the inaugural World Series, Pittsburgh's Bucky Veil became the first relief pitcher in World Series history.

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