Not too sure how it works.... I think the ave. now is worked on your last 10 games say. not sure about that but....
Maybe to put it simple from what i've noticed... if you shoot over your Ave. nothing happens..eg your 41 you shot. Every time you shoot under..eg the 35's you shot, then your ave. will drop.
Before the change, your Ave. would have been going up and down like a yo-yo. Now, if shoot a good score your Ave. will drop, within reason and if you shoot a bad score your Ave. will stay the same.