Starting Pitcher
The man who begins the game, and the only player whose job is defined by a calendar.
What it actually is. The starting pitcher throws the first pitch of the game and stays in until the manager takes him out. Clubs carry five of them in a rotation and each pitches roughly every fifth day, with four days of rest in between. A starter is expected to go five or six innings, and he must complete five to be credited with a win.
What somebody who knows the game gets out of it. The starter's job has shrunk and the reason is measurable rather than cultural. A pitcher facing a lineup for the third time gives up meaningfully more than he did the first, because hitters adjust within a game, and that times through the order penalty is worth roughly a third of a run. Once clubs quantified it, the rational move was to hand the third pass to a fresh reliever, which is why the six inning start became the target and why the opener exists at all.
The numbers worth knowing. A rotation regular makes 30 to 32 starts and throws 170 to 200 innings. In 1980 the leaders threw over 300. A hundred pitches is the informal ceiling and the third time through the order usually arrives between the fifth and sixth innings.
What people get wrong about it. The win is a terrible way to judge a starter and always was. It requires five innings, a lead when he leaves and the bullpen holding it, so it measures his team as much as him. A pitcher can throw seven shutout innings and get nothing, which is why nobody serious has used wins to evaluate pitching for twenty years.
At Little League and travel ball. There is no rotation in youth baseball, there are pitch counts and required rest. A twelve year old throwing 66 pitches needs four calendar days before he can pitch again under Little League rules, and USSSA counts differently. The constraint that decides a travel weekend is arms, which is what the Pitch Planner on this site exists to solve.
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