WebBall.com - Screwball vs Curveball

A different spin on breaking pitches

Which Pitch & Why	Curveball	Screwball
Grip	More than one way to grip the ball - two fingers on long seam is easiest.	More than one grip possible - fingers slightly spread seems easier.
Forearm Rotation	270 degrees outward	90 degrees in
Forearm Muscles	Ulna bone leading forearm with flexor carpi ulnaris muscle the prime mover muscle. Muscles must be developed sufficiently with flexibility and strength.	Radius bone leading forearm with flexor carpi radialis muscle the prime mover muscle. Muscles must be developed sufficiently with flexibility and strength.
Elbow	Must be > 90 degrees. More closed causes forearm flyout when starting upper arm acceleration phase.	Easier to maintain proper 90 degrees. Will not suffer from forearm flyout.
Shoulder	Bending elbow leads to a vertical forearm which results in a shoulder bounce that stresses attachment on top of humeral head.	Easier to rotate humeral head and raise forearm to horizontal rather than vertical. Will not suffer from shoulder bounce.
Palm Launch	Curls in palm facing head. After release palm forced up	Facing out. After release palm facing downward
Wrist	Ulnar flexion	Radial flexion.
Fingers	Release over index or middle finger Drive to release with the ring finger side	Release using only tip of middle finger Drive to release with the index finger side
Thumb	Goes over top of baseball Helps tip of finger control the baseball through release.	Goes under baseball Leaves only tip of middle finger to control the release.
Spin Axis	Horizontal spin axis	Horizontal spin axis