Weren't you the one who stated that he did improve? I was merely disagreeing with you (because it's what I believe). Do you really have any "evidence" toward his defensive improvement? Even if he has improved, it isn't enough to be a legit center. Amare Stoudemire can show you how many rings a good-scoring center without convincing defense can garner you.
Let's look at blocks (given that Rp30 went
down from last season vs. the previous one): they are up to 1.6 per 30 from 1.2 per 30. Blocks is an imperfect measure of defense, but if that's your basis for him improving, your basis falls far short.
How about opponent's production (as per 82 games)? 18.0. OK, but not outstanding.
Perhaps the most damning is points allowed per 100 possessions: 113 when he's on the court last season and 106 when he's off, for a difference of >7. That's worse than the previous season (113 vs. 111). Obviously teammates play a factor, but that's not a pattern that supports your stance.
https://www.82games.com/1011/10UTA15.HTM
https://www.82games.com/0910/09MIN12.HTM
If you have the data on how many times he got burned on help defense, then we could compare it; I don't. Until then, my claim is now far more substantiated than your data-deficient stance.