Base running

Base runners may attempt to advance at any time while the ball is alive, even before or while the pitcher is throwing a pitch.

The catcher—or pitcher, in lieu of delivering the pitch—often tries to prevent this by throwing the ball to one of the infielders in order to tag the runner.

If the runner attempts to advance to the next base but is tagged out before reaching it safely, he is caught stealing.

However, any hesitation or mistake on the part of the fielder may allow the runner to reach the base safely.

[3] A take-out slide tries to use a collision with a fielder to keep him from taking additional action, such as throwing to achieve a double play.

However, this move, when made independently of the attempt to reach the base, has been illegal since 2016 because of the potential for injury.

The most baserunners allowed by a pitcher in a game since 1901 is 39, by Eddie Rommel, who pitched 17 innings in relief for the Philadelphia Athletics to defeat the Cleveland Indians, 18–17, on July 10, 1932.