I've always known IQ has a big impact on a player but I'm starting to think that biggest impact is on rebounding, anybody agree?

For example I was in a recruiting battle so I promised a start to a freshman who didn't know my offense so his IQ started as an F. He's very athletic but has a low reb rating for a starting big man, however I think with his mid 60s ath, he should be able to get at least 3-4 rebounds a game despite a reb rating that started at 58 and is now up to 60. Instead he has gotten just 5 total rebounds in 6 games including exhibition starting and playing about 14 minutes a game.