Spin Axis
Spin axis is the imaginary line around which a pitched ball rotates, determining the direction of movement — a horizontal axis creates vertical break (rise/drop), a vertical axis creates horizontal break (curve/screwball).
Every moving pitch has a spin axis tilted at some angle between purely vertical and purely horizontal. A tilted axis produces break that is a combination of horizontal and vertical movement — a "cutting" rise ball or a "fading" drop. Pitchers who understand spin axis can intentionally shape pitches by adjusting their wrist-snap angle at release. Catchers use the seam orientation of the ball leaving the pitcher's hand to predict break direction.
Example
The pitcher adjusts her wrist snap from a 12-o'clock axis (pure rise) to a 10-o'clock axis, giving the pitch a rising-and-running action that moves up and in on right-handed hitters.
Related terms
- Wrist Snap – PitchingThe wrist snap is the final acceleration of the wrist and fingers at the moment of release in the windmill delivery — the primary source of both pitch velocity and spin.
- Rise BallA rise ball is a fast-pitch pitch thrown with backspin so it appears to climb as it nears the plate, tempting hitters to swing under it.
- Curveball – Fast-PitchA curveball is a fast-pitch pitch thrown with lateral spin that causes the ball to break sharply to one side as it reaches the plate, disrupting a hitter's timing and eye-line.
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