I agree he took the Mavs to a level Don Nelson could never take them, but did he really make the team better? He got them to pay attention on defense, that's about it.
Was Dirk better because of Avery? Was Jet? Howard got better under Avery, then his complete freefall happened under Avery as well.
Marquis Daniels regressed under Avery. Dampier never played well under Avery, but that's hardly Avery's fault. Diop had one good year under Avery, which was motivated more by money than anything else. Devin Harris played well but never played to his potential under Avery.
I don't see how Avery did anything to develop the talent on the roster. He was great at motivating the team and getting them to buy into his defensive philosophy for a couple years, but I personally think Avery is a horrible hire by New Jersey. He won't develop any of that young talent.