When put in a position to succeed, he can do well enough, as evidenced by his 20 goals playing predominantly on Matthews' wing. Thing is, that handcuffs 34 a bit, as he plays better with better players (who woulda thunk it?).
Problem for Brownie is that, with all the depth and talent we have on the wings, he is unlikely to be getting that kind of opportunity again. Right now, in Toronto alone (NHL and AHL), there are Marner, Nylander, Hyman, Marleau, Kapanen, Johnsson, and Grundstrom who all are/have the potential to be better than Brown in very short order. All of Hyman, Marleau, Kapanen and Johnsson (possibly Grundstrom as well) can fill the same roles that Brown does, with at least one skill that stands out above everything he has, and all put in just as much effort on the ice.
If I'm Dubas, as much as I like Brown the person, and even the professional, I look to move him to a team that is looking for offensive depth, that sees a youngish player capable of putting up 20 and can PK, and get some solid assets before they see him for what he is, which is a nice piece, but not a core player on a contending team. I look at him similar to Versteeg. Nice support player, but not someone you keep around once they get surpassed on the depth chart.