In baseball or softball, a starting pitcher or starter is the first pitcher in the game for each team. A pitcher is credited with a game started if they throw the first pitch to the opponent's first batter of a game. A pitcher who enters the game after the first pitch of the game is a relief pitcher. Starting pitchers are expected to pitch for a significant portion of the game, although their ability to do this depends on many factors, including effectiveness, stamina, health, and strategy.
A starting pitcher in professional baseball usually rests three, four, or five days after pitching a game before pitching another. Therefore, most professional baseball teams have four, five or six starting pitchers on their rosters. These pitchers, and the sequence in which they pitch, is known as the ''rotation''. In modern baseball, a five-man rotation is most common.〔For an evaluation of the relative merits of a four-man and a five-man rotation, see Rany Jazayerli, "Doctoring The Numbers: The Five-Man Rotation, Part 3," BaseballProspectus.com (August 30, 2002).()〕
Under ideal circumstances, a manager of a baseball team would prefer a starting pitcher to pitch as many innings as possible in a game. Most regular starting pitchers pitch for at least five innings on a regular basis, and if a pitcher is unable to do so, there is a high probability that he will, in the future, be relegated to duty in the bullpen. In modern baseball, a starting pitcher is rarely expected to pitch for more than seven or eight innings, at which point, responsibility for the game is passed to ''relief'' pitchers, including ''specialist'' pitchers such as setup pitchers and closers.
Often, a starting pitcher is subject to a pitch count, meaning the manager will remove him from the game once he has thrown a specific number of pitches. The most common pitch count for a modern pitcher is in the neighborhood of 100, and it is now rare for a starting pitcher to throw more than 125 pitches in a game. Pitch count limits are especially common for starting pitchers who are recovering from injury.
In the early decades of baseball, it was not uncommon for a starting pitcher to pitch three hundred innings or more, over the course of a season. In addition, there are accounts of starting pitchers pitching on consecutive days, or even in both games of a doubleheader. It is believed that these feats were only possible because pitchers in the early years of the game, unlike modern starters, rarely threw the ball with maximum effort.
A starting pitcher who can be counted on to consistently throw many innings is known as a ''workhorse''. An example of a modern-day workhorse pitcher is Roy Halladay, who was the active leader in both complete games thrown and shutouts before his retirement in 2013.〔(【引用サイトリンク】title=Halladay goes for 61 against Nationals )〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』