What Is a Curveball in Baseball? Spin and Break
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TL;DR
The curveball is a breaking pitch with pronounced downward movement. Pitchers use spin and a lower speed to make the ball appear hittable before it drops below the barrel.
How it moves
The grip and wrist action create a spin axis that produces movement through the Magnus effect and gravity. Pitch shape varies with release angle, velocity and spin efficiency.
Curveball versus slider
A slider is usually faster with more lateral movement, while a curveball emphasizes downward break and a larger speed difference from the fastball. Pitch labels overlap between pitchers.
How hitters identify it
Hitters watch the release and tunnel, not the late break alone. A curveball that starts on a fastball line can force an early swing decision.
When pitchers use one
A curveball can begin an at-bat for a strike or finish a hitter below the zone. Poor location leaves it hanging in a dangerous hitting area.
Related baseball analysis
See fastballs, ERA, walk-offs and the infield fly rule.
Sources
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