Well, if Peter Vescey can copy his articles off a Lakers blog, I'm pretty sure I can come here and see what frustrates Hawks fans!
Marvin's a good dude and is really just doing what the coaching staff is asking him to. He really should take it to the basket more often, but the team is trying to establish Zaza and Smoove in the paint, which doesn't really leave much proper space for three slashers. Marvin is one of the best shooters in the league as far as in his form. He's got a Michael Redd-like consistency to it. It'll come together for him soon, and when it does I'm sure he'll be looking to get people in the air with a pump fake and then create a little.
IMO, the Hawks are not using him to the best of his ability. He needs to have the ball in his hands a little more to set up other guys. It's really a shame his passing isn't being utilized more often. I guess that comes down to the Hawks getting more movement as well.