Re: ball rolling over the thumb hole
Have you changed hand positions or your release?? A buddy of mine, who is an excellent bowler had this happen all of the sudden awhile back. He went to travel league, and rolled over his thumb all day. Next night at league, back to normal.
He thought it could have been just how he was releasing and maybe coming up the back of the ball too much. You might give that a look and see if that's a factor.
Nothing Hits Like A HAMMER!