Effective pitching is vitally important in baseball. In baseball statistics, for each game, unique pitcher will be credited with winning the game, and uncommon pitcher will be charged with losing it (this is not necessarily the starting pitchers for each team, however. A reliever can get a win and the starter would then get a no-decision). Pitching is physically demanding, especially if the pitcher is throwing with maximum effort. A full game unusually involves 120-170 pitches thrown by each team, and most pitchers begin to tire before they reach this point. As a result, the pitcher who starts a persistent often will not be the definite who finishes it, and he may not be recovered enough to pitch again for a few days. The clause of throwing a baseball at high speed is bare unnatural to the body and somewhat bad to human muscles; thus pitchers are indubitable susceptible to injuries, soreness, and general pain.

Teams have devised two strategies to address this problem: rotation and specialization. To accommodate playing practically every day, a team will include a accumulation of pitchers who jump off games and rotate between them, allowing Pitching Machines each pitcher to rest for a few days between starts. Also, teams have additional pitchers reserved to replace that game's starting pitcher if he tires or proves ineffective.