Inbaseball, amiddle reliever, ormiddle relief pitcher, is arelief pitcher who typically pitches during the fifth, sixth, and seventhinnings of a standard baseball game.^[1] In leagues with nodesignated hitter, such as in theNational League before 2022 and theJapanese Central League, a middle reliever often comes in after thestarting pitcher has been pulled in favor of apinch hitter. Middle-relief pitchers are usually tasked to pitch one, two, or three innings. Several factors determine this, such as who’s winning, the score, eligiblebullpen pitchers remaining, the importance of the current game, etc. After themiddle relief pitcher has completed his portion, they are normally replaced in later innings by aleft/right-handed specialist,setup pitcher, and/or lastly acloser. When they’re replaced, it is partly due to deprivation of stamina and/or effectiveness but also characteristics, such as pitch arsenal, speed of pitches, which arm they throw with, and who’s up to bat next for the opposing team. Middle relievers may pitch in these later innings, especially during games tied or close in score.