I actually think 85 is fairly accurate for Dirk, based on last season. His numbers were down (granted, mainly due to early-season struggles but it still counts), his defense isn't particularly great and he's seemingly allergic to rebounding. His offensive ratings will still be high so what's the problem?
Just because Dirk's a great scorer, doesn't mean he warrents higher defensive and rebounding ratings just to increase his overall. I was ranting about it earlier; 2K does it with all the stars. To wit: Carmelo Anthony.
I agree with the rest of what you said, though, for the most part.