Cal, i have a comment you really should consider. You're pulling some shots because you're dropping your thumb. You're dropping your thumb because you are trying too hard to get some reaction on the ball. You're timing is off because you're trying to force the ball through muscle. There is a simple (sure fire) fix to this. Assuming you are square and your backswing isn't forcing your shoulders to open up, it's all in the hand. When your hand is consistantly in a leveraged position, everything relaxes. I know you probably won't (most people are just too darn stubborn) but you really should get a good wrist brace. Gadgit by storm is what i use and it works. If you drop your thumb wearing that, well it won't take you long to figure out not to drop your thumb. You try it, if you don't like it I'LL BUY IT OFF YA. BTW, i'm metguy (in case you don't know).

Just saw this comment Jeff. Not sure what you mean by dropping the thumb, but not all of the misses left are actual pulls. Many times it's other issues like body alignment and swing plan issues. Some shots are muscled but some are swinging free and a matter of body lean, almost upright tends to bring the ball in two or so boards but still projects the ball down the lane correctly. The wrist brace isn't going to happen, I've tried them before. They made my wrist turn early, felt like they were going to come off on every shot, I would have to get all 4 of my balls re-fitted and makes it very difficult just to get the fingers and thumb into the ball. My hand does normally stay in a strong position and a bowler can get a better release without them. I just really need to get out and put in some quality practice time since for several years that's been non-existent.