Its tough to say whether he has just had bad luck, or if he just is not good enough to lift a team to be a winner. But regardless, I think it is hardly debatable that if he doesn't start winning soon, he is going to have a tough time shaking the loser label, much like Shareef Abdur-Rahim.
Maybe the losing rubs off on him, maybe he is contributing to the losing, but for whatever reason, it is not working, and I would not want to build a team around him because of that.