Blocking and speed. Coffman isn't a particularly fast TE. He has fairly average speed. And he never really blocked at Cincinnati. And the problem is that unless you play in a system that is willing to split their TE out wide often, then Coffman doesn't bring a lot of the traits you want in a TE. The COlts did that with Dallas Clark, NE does it with Hernandez, GB with Finley, and Cleveland has dabbled somewhat with Evan Moore a bit. But other than them, every body else wants inline TEs, and thus Coffman doesn't fit that mold.
But in terms of ball skills and ability to go and get a football, comparing him to Gonzalez is not crazy. You put a ball up in his area, Coffman will go and get it.
Unfortunately, I don't think there's a chance Coffman sticks in Atlanta, not unless the Falcons are having a change of heart in the type of offense they want to run. He'll run into the same problem he had in Cincinnati which is not being a fit for what they want.http://youtu.be/Oto3BMYPP1w