Thanks Yoda for the useful quote. So (to answer Mike O's question) the center of gravity of the ball does move during impact interval?
If that's true, then according to Mike, there's a contradiction in TGM. But I think this hook-face thing Homer talks about on page 24, which diverts the ball from it's true tangential path, should save the day...2-D-0 has always been foggy to me.