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Intermediate

Pitch Spin

Pitch spin refers to rotation imparted on the ball at release. Intentional spin to alter the ball's flight path is an illegal pitch in slow-pitch; minimal, incidental backspin is generally permitted.

Because slow-pitch pitchers cannot rely on speed or movement, some try to add spin to produce a wobble or curve off the arc. Associations prohibit intentional wrist-snapping or finger-spin that causes visible curve. Incidental backspin from a clean release is legal. Hitters benefit from reading spin early because a wobbling ball is harder to time, while a clean rotation signals a true arc descent.

The umpire calls illegal pitch after noticing the pitcher snap the wrist sideways, imparting visible sidespin that curves the ball off the straight arc.

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