Very disappointing overall from Brown. However, still some positives. First, he looked a bit hobbled so you might be able to cut him a bit of a break(only a tiny one, youre gonna have to play through knocks in the NBA). His shot looks nice in catch and shoot situations, he needs to figure out how to keep his form and locate the basket when he shoots off the dribble and when curling of screens etc. his burst is just as advertised and hes actually quicker on his feet and most importantly his handle seems much better than I expected. This combination suggests to me that he will be able to get to the rim at will in the NBA.
He needs to learn much better defensive fundamentals. With his tools he should be a defensive stopper, not just OK. Then the big one. He needs to do a better job at the rim/in the pain. He blows by his defender with ease and seems to always go right to the rim with no plan. It might be that the game is too quick for him. If the game slows down for him, he will finish much better and be able to avoid charges and create easy baskets by dishing the ball in the paint.
Still optimistic about the kid. The brightside is that 2 of his weaknesses (ballhandling and shooting) seem to be a bit overblown while his strengths (really just athleticism) seems to be legitimate.
Listen, in fairness to the kid, I thought that he looked slightly slower out there, although maybe that's just me (feel free to give your views on this, btw

). Is it the knee? Probably, but let's see if he plays tomorrow. If he doesn't, well, like you said, it doesn't completely excuse his performance, but I'd cut him some slack.