Battery error

A battery error is a pitch that the catcher fails to handle cleanly that results in a baserunner successfully advancing one or more bases, or in the batter reaching base on a dropped third strike. Battery errors are classified as either passed balls or wild pitches depending on whether the official scorer rules the catcher or pitcher to be at fault. According to the Official Rules (Rule 10.15):

a) A wild pitch shall be charged when a legally delivered ball is so high, or so wide, or so low that the catcher does not stop and control the ball by ordinary effort, thereby permitting a runner or runners to advance. (1) A wild pitch shall be charged when a legally delivered ball touches the ground before reaching home plate and is not handled by the catcher, permitting a runner or runners to advance. (b) A catcher shall be charged with a passed ball when he fails to hold or to control a legally pitched ball which should have been held or controlled with ordinary effort, thereby permitting a runner or runners to advance.

Although described as battery errors, passed balls and wild pitches are counted separately from other errors. See Rule 10.14:

(f) Because the pitcher and catcher handle the ball much more than other fielders, certain misplays on pitched balls are defined in Rule 10.15 as wild pitches and passed balls. No error shall be charged when a wild pitch or passed ball is scored. (1) No error shall be charged when the batter is awarded first base on four called balls or because he was touched by a pitched ball, or when he reaches first base as the result of a wild pitch or passed ball. (i) When the third strike is a wild pitch, permitting the batter to reach first base, score a strikeout and a wild pitch. (ii) When the third strike is a passed ball, permitting the batter to reach first base, score a strikeout and a passed ball. (2) No error shall be charged when a runner or runners advance as the result of a passed ball, a wild pitch or a balk. (i) When the fourth called ball is a wild pitch or a passed ball, and as a result (a) the batter runner advances to a base beyond first base; (b) any runner forced to advance by the base on balls advances more than one base, or (c) any runner, not forced to advance, advances one or more bases, score the base on balls, and also the wild pitch or passed ball, as the case may be; (ii) When the catcher recovers the ball after a wild pitch or passed ball on the third strike, and throws out the batter runner at first base, or tags out the batter runner, but another runner or runners advance, score the strikeout, the putout and assists, if any, and credit the advance of the other runner or runners as having been made on the play.