In baseball, a pickoff is an act by a pitcher or catcher, throwing a live ball to a fielder so that the fielder can tag out a baserunner who is either leading off or about to begin stealing the next base.
A pickoff attempt occurs when this throw is made in an attempt to make such an out or, more commonly, to "keep the runner close" by making it clear that the pitcher is aware and concerned with the runner's actions. A catcher may also attempt to throw runners out who likewise "stray too far" from their bases after a pitch; this can also be called a pickoff attempt. A runner who is picked off is said to have been caught napping, especially if he made no attempt to return to his base. A pickoff move is the motion the pitcher goes through in making this attempt; some pitchers have better pickoff moves than others.
Pitchers in professional baseball use the pickoff move often, perhaps several times per game or even per inning if speedy baserunners reach base. Pitchers with more confidence in their ability to eliminate batters directly via strikeouts or flyouts use fewer pickoff attempts. In lower-skilled amateur games, the pickoff move is less common due to the potential for an error if the pitcher throws wild or the fielder fails to make the catch. In youth leagues that do not allow leading off, such as Little League and Cal Ripken League, the need for a pickoff move is eliminated. A pickoff may result in a rundown.