[rogerdodger]

I have had this issue as well, even wearing down cord grips in the right thumb area. An instructor told me it is from the club going off-plane in the transition, and the right thumb tightens against the grip to prevent it from twisting. I don't know if that is correct, but when I don't lay the club off in the transition, which is my main problem, I do not have the wearing down. Also, it only is present on my long clubs, which seems to support this theory.