If you have a very "inflexible" thumb, you WILL need to use reverse pitch to get the GOOD feel you're looking for. Squeezing is a necessity to hang on to the ball. This gives YOU control of the ball, not the ball controlling you. The key here is to MINIMIZE the squeezing.
This is done with bevel, allowing your thumb to get deeper in the hole(a novel idea), and some good ole fashioned bowlers tape. If the hole is snug, you minimize the squeezing and won't have to squeeze the ball to the point of it becoming a problem. If the ball hangs on to your hand with no squeezing, you literally will have to force the ball off your hand and be absolutely perfect with your timing and everything to get the ball off cleanly. This is impossible to do consistently.
Plus the ball will only come off your hand 1 way. This is not good.
You want to be able to make changes in your hand position and even changes to your fingers in the hole placement to change the way the ball comes off your hand. These changes will allow you to use the same ball, but get different ball reactions using different hand positions in relationship to the gripping holes.
Using bevel, tape and a slightly more reverse pitch, allows you to accomplish releasing the ball different ways, while still coming out of the ball as clean as silk. Good luck. =:^D
