I was guilty of the same thing. Coach told me it was because of the fingers being too high up on the ball at release. his cure was to get me to work on keeping a firmer wrist. I also tended to chicken wing trying to "help" the ball and ended up over rotating.
Besides keeping the wrist firmer, he had me do the water bottle drill (easier to demonstrate than to explain). For the water bottle drill, take a 20 oz or similar empty bottle. Place the bottle in the hand so the top faces away from your body when the palm is up. Hold the arm at your side and then go through the regular armswing. When the just passes the hip, the hand rotates so the bottle is now in an upright position.
The next step was to release the thumb as you rotate the bottle and return it to the bottle before the bottle flies. The thumb when placed back on the bottle is pointing to the top of the bottle. It sounds weird, but basically it is because the hand is turning not the thumb.
Another drill he tried with me, but I never was successful at it is to use a nerf football instead of the bottle and spiral the ball. I hope something in this helps.
Bookmarks