Well, I was in a slump, having problems with my thumb hole. So I took my balls to my local pro shop and he said it was a wonder I was even bowling with them.  He re-did the thumb holes giving them an oval insert, and replaced the fingertip inserts on one.  Now I have went from bowling in the 140's to bowling in the 180-200's.  Unbelieveable!!!  Bowling is fun again and with no pain with my thumb.  I had never heard or seen a oval insert before, but it sure works. Gives me more lift on the release too.  I love it.  I am going to take some bowling lessons within the next month.  I'm going to be a force to reckon with time it's all over! lol