A pitcher is credited with an appearance if he pitches in a given game. When a pitcher enters the game -- barring an injury while warming up -- he must face at least one batter. When crediting pitchers with an appearance, it does not matter whether the pitcher started the game or pitched in relief.
Baseball's pitching appearance leaders tend to be specialized relievers. For instance, a lefty who is especially adept at getting out left-handed hitters often enters a game to face one or two specific batters. This puts less of a tax on his arm relative to the tax experienced by starters and many relievers, who often pitch an inning or more.
Appearances can be tricky, because managers inevitably want to limit the total number of appearances by their pitchers to keep them fresh. But not every appearance is created equal. With this in mind, managers must determine when their pitchers are taxed and in need of a day off.
Watch: Mariano Rivera makes his 1,000th career appearance, becoming the first ever to do so with one team.
In A Call
"game," "game pitched"