In baseball, a wild pitch (abbreviated WP) is charged to a pitcher when a pitch is too high, too short, or too wide of home plate for the catcher to field with ordinary effort, thereby allowing the batter and/or one or more baserunners to advance or to score. When (a) first base is unoccupied and/or (b) there are two outs, the catcher must catch the third strike in order to retire the batter; if a wild pitch occurs on such a third strike, the pitcher is credited with a strikeout, but the batter is not retired—he may attempt to advance to first base and must be tagged with the ball or forced at first in order to effect an out.
A wild pitch usually passes the catcher behind home plate, often allowing runners on base an easy chance to advance while the catcher chases the ball down. Sometimes the catcher may block a pitch, and the ball may be nearby, but he simply cannot find it for one reason or another.
A closely related statistic is the passed ball. As with many statistics, whether a pitch that gets away from a catcher is counted as a wild pitch or a passed ball is at the discretion of the official scorer. The benefit of the doubt is given to the catcher if there is uncertainty; therefore, most of these situations are scored as wild pitches.
A wild pitch may only be scored if one or more runners advance a base. If the bases are empty, or the catcher retrieves the ball quickly and the runner(s) are unable to move up, a wild pitch is not charged. A runner who advances on a wild pitch is not credited with a stolen base unless he breaks before the pitch is delivered.
Nolan Ryan is generally considered the career leader in the category, throwing 277 wild pitches over his 27 years in Major League Baseball. He also led the league in the category in six different seasons. However, the all-time record truly belongs to Tony Mullane, who threw 343 in the early years of the game from 1881 to 1894. Mickey Welch is next on the career list with 274. After that, a dropoff occurs, with the next highest pitcher, Tim Keefe, only having 233 all-time wild pitches.
Bill Stemmyer still holds the single-season record, throwing 63 wild pitches in 1886. Since 1900, however, the highest total in a season has been 30 (by Red Ames in 1905). The modern record in a single game is 6, held by three different pitchers.