Stolen base

From BR Bullpen

A stolen base occurs when a baserunner advances to the next base without the ball having been hit into play or a fielding error. Stolen bases are awarded at the discretion of the official scorer.

Typically a stolen base is the result of the runner running to the next base simultaneously with the pitch being thrown and reaching it before being tagged by the ball thrown by the catcher to the base the runner is trying to reach. A stolen base can also occur while the catcher is relaying the ball back to the pitcher, or when a pick-off is attempted.

A baserunner can only attempt to steal an unoccupied base, unless there is a double steal. If the runner fails in his attempt, it is a caught stealing. In situations wherein the opposing team does not attempt to catch a baserunner stealing, then the official scorer may not award the baserunner with a stolen base, and instead the advanced base is scored as defensive indifference.

A number of factors have an impact on whether a stolen base attempt will be successful: the speed of the runner, the quality of his jump from the base, the strength of the catcher's arm, and the speed of the pitcher's motion to home plate. It is easier to steal on a breaking ball than on a fastball. If the defensive team expects that a runner will attempt to steal, it can reply by either attempting a pick-off play, or by calling for a pitch-out.

As a strategy, the stolen base has risen and fallen in popularity over the years. It was a major part of the game in the Deadball Era, fell out of favor from the 1920's until the 1950's, then enjoyed its heyday from the 1960's to the late 1980's. With the offensive explosion of the 1990's, and sabermetric research indicating that it is only a useful strategy when the success rate is higher than two-thirds, the stolen base has fallen into disfavour. It is typically used more often in a low run scoring environment and is considered a small ball tactic.

A stolen base is often abbreviated SB.