- For the CIA informant, see curveball (informant)
The curveball is a type of pitch in baseball thrown with a grip and hand motion that induces extra rotation on the ball causing it to "break," to fly in a more exaggerated curve than would be expected. The pitch is slower than a fastball, and this difference in velocity also tends to disrupt the hitter's timing. Good curveballs often seem to drop sharply with a sharp rotation as they reach the plate, making the batter swing above it. The rotation on a curveball should be in the opposite direction as that of a fastball so the hitter cannot easily distinguish between the pitches; as such, the drop on such a ball should be 12 to 6 on a watch (although many pitchers are successful with a curve ball that breaks down and away from the batter, rather than straight down).
Ideally, a curveball will have the most break when it reaches the plate, thus making it hardest to hit. A curveball that fails to break soon enough is called a "hanging curve" and is much easier to hit. Also, batters anticipating a curveball may try to move forward (closer to the pitcher) in the batter's box to hit the curve before it breaks.
The curveball rotation is produced when the pitcher snaps his wrist downward at the moment of release, causing the ball to "roll" off the pitcher's hand. The pitcher's palm typically faces up during the followthrough after releasing a curveball.
A screwball is similar to a curveball, but thrown from the back of the hand in order to impart opposite rotation and opposite movement. The knuckle curve is a variant of the curveball.
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