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The Myth Of The Evil Screwball


In talking about pitching with different people, I keep running across the idea that the screwball is extremely hard on the arm.

This is not the case.

The reality is that the screwball is actually very easy on the arm. Because you pronate (rotate counter-clockwise) the forearm as you release the ball, you keep the bones of the elbow from slamming together. This is in sharp contrast to pitches like the curveball or the slider in which the forearm is supinated and the radius slams into the Humerus as a result.

I think this myth got started by people looking at pitchers like Fernando Valenzuela who threw the screwball and had arm problems. They leaped to the conclusion that the screwball was the cause rather than things like Valenzuela's advanced age and his curveball.

If you want proof that the curveball isn't dangerous, look at the career of Dr. Mike Marshall. He was one of the most prolific screwballers and never had a serious arm problem over the course of his 16-year career.

Professional football quarterbacks also routinely pronate as they release their passes. That is how they throw the ball with such a tight spiral.

All of this is a shame because a screwball is a perfect pitch for a left-handed pitcher to throw. Similar to a right-handed pitcher's slider, a screwball's movement causes it to move down and out to RH batters.

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