But if you're directly trading Iguodala for McGrady, I think they can be directly compared, whether or not Iguodala is a legitimate cornerstone player (in fact, that's part of the argument).
And Brand's teams really have had a very small amount of success, regular season or playoffs, in his 9 seasons in the league. I don't think it's ultimately fair to level McGrady a flash in the pan without applying the same criticism to Brand. Whether or not someone's viewed as a "superstar" or not really doesn't matter, since Brand is going to be the best player on the team as currently constructed.