First, ratings are not affected by TIE/Normal/CT, so the difference wouldn't be bigger. Second, his rebounding team rating is low because of the tactic, but rebounds are still affected by the individual skills of all players. And last, but not least, the level of enthusiasm has an effect there as well, so if you come in with very low enthusiasm, or he comes in with very high, or both, he can possibly outrebound you.
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."