This has already been addressed pretty well by Ty, but I wanted to emphasize the primary difference between Brewer and Oladipo (besides not having the one of the most comedically busted shots in the NBA [though he's gotten impressive results considering that, but that's not saying much]) is heart. Brewer was soft. His motivation defensively was to play passing lanes and contain his assignment, the latter usually suffering because of the former. Brewer didn't rebound particularly well either. Oladipo just goes after everything. Boards hard, plays physical defense, but is athletic enough to keep his space and still keep with his assignment. The guy just won't be denied most of the time.