agree with above
proper fit and the proper use of tape to relax the grip pressure are a must
i hadn't used tape in 25+ years, i found out that my grip was to short and i was squeezing it, no matter how hard I tried, i couldnt come out the ball clean.
Now with the proper span and learning how you use tape, its much, much better.
the more you use your thumb to squeeze the ball, the more you flex your thumb and the larger your knuckle gets inside the thumb hole.
ideally, you want the back of the thumbnail to touch the opposite side of the thumbhole.
this assures that the thumb is straight, i have to tape my thumb pretty tight these days to hang on to it