re: Why doesn't Gentry get more criticism?

You don't have to "suspect". All stats are readily available on the inter webs. Quite easy to find, actually

You will find, after your search, that his sharp decline in efficiency was due to his decline in the 3-10 foot area, not because of the increased jump shots

But don't take my word for it. Go look for yourself.

If you want to critique Gentry with regard to AD's efficiency, a legit criticism would be that he doesn't encourage offensive rebounds, where AD traditionally got a lot of easy points