I think the addition of Grant Hill has really made us see Doris's faults even more because Grant does all of the same things offensively that Doris does and Grant does them better. Grant's a better passer, dribbler, jumpshooter, slasher to the basket, etc etc. Grant shouldn't be trying to guard centers like Doris does though. I think Doris's confidence is completely gone because the Suns have other guys that can do what he does and they do it better (Amare's inside scoring, Grant's playmaking).
I don't know how they can do it, but they need to find a way to give this guy a swift kick in the ass. He needs to realize that just because there are other guys that can do what he does, doesn't mean he should stop doing them and just let the other guys take over. We need every guy being aggressive and playing to their strengths and not passing up layups for low percentage shots. Doris is smart and he's got good skills, he just needs the right mentality to make it all work. Maybe they need to put more pressure & responsibility on him like they did the season Amare was out. Let's face it, the Suns can win without him playing well so he probably doesn't feel like an important part of the team.