I've had that problem for over 10 yrs. Here is what I did to almost eliminate the problem.
1.) Put your thumb to the back of the ball. (Meaning, you shouldd feel your thumb nail touching the slug or ball depending on what you use. Add tape as needed so that its a tight fit. With the thumb straight, a tight fit of the thumb felt great.)
2.) Have your span and thumb pitch checked. A lot of peoples span who grab the ball, that I have seen, have been long. It stretches the span causing the bowler to grab the ball in order to hold on to it.
3.) Get a coach to help you out. Maybe its timing issues, maybe its something else. A good coach will be able to diagnose what the issue with your grabbing is.
As stated earlier, I've done all 3 and have done a great job almost eliminating my problem with grabbing the ball. Hope this helps.
aka. Big Daddy Pink, Pink Pinkstofferson, Smooth as Asian Silk, Righty Complex, Big Daddy Wit Da Smooth Head.
I'm man enough to admit I stroke with the left hand and it feels good.
Whooooooo! Go time!
No excuses. Just bowl. High Score wins! Make the Adjustment!
Mullans pro shop Richmond, Va.