You have to remember, that his strengths were basically his athleticism. He was extremely raw, he didn't have the many basic skills that superstars in the league came into.
Wade was a born star, Durant, Carmelo, LeBron, Bryant. These guys are players you don't find very often.
Guys like Joe Johnson, Luol Deng, Danny Granger, Andre Iguodala. These guys are the tier of wings I would put Demar in when it's all said and done, because unlike the stars who were born into very good wing players, these players were MADE into very good wing players. The names above took a while before they could really blow onto the scene as an elite wing player, compared to Durant, LeBron, Bryant, who were drafted basically as established stars.
There are players who are already stars, and there are players who work hard to get there. Patience is key if you want the work to be shown. I think people are underrating the time it takes to really work on one's game to become better, especially with the rawness Derozan came into the league with.