Can you point out any basketball reasons why Brewer isn't an elite wing defender? What does he do worse than elite wing defenders?
The short answer is that he is not strong enough to keep guys out of the lane, and while he has active hands and looks good playing defense, gives up way too many easy shots. He also has way too many lapses, where he will stop someone for a couple seconds, and then will let up just enough to give up a basket, or make a dumb foul.
He has great defensive talent, but has not yet shown the consistency or well-rounded defensive game to be considered elite.