A curveball is a breaking pitch that has more movement than just about any other pitch. It is thrown slower and with more overall break than a slider, and it is used to keep hitters off-balance. When executed correctly by a pitcher, a batter expecting a fastball will swing too early and over the top of the curveball.
Most professional pitchers possess either a curveball or a slider -- and some possess both breaking pitches. Having a breaking pitch, like a curveball, is an essential component to a professional starter's arsenal, because it keeps the hitter off-balance and unable to commit to gearing up exclusively for a fastball.
The curveball has been one of the most commonly used pitches throughout baseball history, and the universally accepted signal for a curveball is a catcher putting down two fingers.
The pitch is so well known in American culture that the phrase "throw a curveball" has emerged as an idiom. Like the goal of pitchers when throwing the pitch, the idiom "to throw a curve" means to trick someone with something unexpected.
A curveball can be thrown with a number of different grips. Some pitchers possess curveballs with a sweeping, sideways trajectory, while other curveballs break straight downward. (These are known as 12-to-6 curveballs.)
The slider and the curveball are sometimes confused because they generally have the same purpose -- to deceive the hitter with spin and movement away from a pitcher's arm-side. (When a pitch seems to toe the line between the two, it is referred to in slang as a "slurve.")
Like a slider, a curveball is thrown by a pitcher with a wrist snap and spin. A curveball that doesn't break as much as a pitcher hopes is referred to as a "hanging curve" or a "hanger" and is much easier for the batter to hit because of its straight trajectory and sub-fastball velocity.
Watch: John Smoltz demonstrates how to throw a curveball.
When pitchers first began throwing the curveball in the mid-1800s, it was considered deceptive and dishonest, but because it could not be outlawed with a specific rule, the pitch persisted and eventually became a staple of the game. It's often debated as to who threw the first curveball, with most historians giving the accolades to Hall of Famer Candy Cummings. The first well known documentation of the pitch came in the New York Clipper. In 1869, the newspaper described Phonney Martin as an "extremely hard pitcher to hit for the ball never comes in a straight line, but in a tantalizing curve."
In A Call
"curve," "hook," "deuce," "breaking ball," "slow breaking ball," "bender," "number two," "Uncle Charlie"