The bevel will contribute to it more, because it lets your thumb socket slide forward and out of position, thereby making it so you HAVE to grip for the pad of your thumb to come in contact with the thumbhole. Your thumb socket needs to be and stay directly above the thumbhole. If your thumb is pulling out and forward, then trying not to grip it will be really hard. Try reslugging one ball, shorten your span 1/16, go light on the bevel, and even without messing with your pitches, that should get you on the right track. With your thumb properly inserted in the thumbhole, you should only be able to see your thumb socket.