split-finger fastball or splitter is a pitch in baseball and a variant of the straight fastball. It is named after the technique of putting the index and middle finger on different sides of the ball, or "splitting" them. When thrown hard, it appears to be a fastball to the batter, but suddenly "drops off the table" towards home plate—that is, it suddenly moves down, towards the batter's knees. It was made famous by Hall of Fame Chicago Cubs and St. Louis Cardinals closer Bruce Sutter, who would be the first of many pitchers to make it a so-called "bread-and butter" or "lights-out" pitch of his repertoire. Sutter claims that while he was in the Cubs' farm system, a minor-league pitching instructor named Fred Martin saw Sutter favouring his elbow. As Sutter was recovering from recent arm surgery, Martin encouraged Sutter to try throwing the split-finger pitch, reasoning it would place less duress on his arm. It is thrown today by many pitchers, including Roger Clemens, John Smoltz and Curt Schilling, a reflection of its popularity amongst power pitchers; Clemens's splitter, one of the tougher pitches in the history of baseball, has been a key reason for his continued success into his early forties. The motion of a split-finger pitch is similar to the outlawed spitball, and at one time the pitch was known as the "dry spitter".
Oakland Athletics right-hander Rich Harden has gained notoriety for his splitter, which features a bizarre knuckling action in midflight. It has been occasionally referred to as the "ghost pitch" and the "spluckle" (a portmanteau of splitter and knuckleball, coined by former Harden teammate Adam Melhuse).
A related pitch is the forkball, which has more of a tumbling action.
A split finger fastball is more of a hard breaking pitch than a fastball.