there are no sure things in the draft. Mack would be an enormous reach at 11 (a bigger reach than Pettigrew) and, at that, Mayock lists him only as the 3rd best center in the draft (for what little that is worth)
I think we will go DE unless there was a run in the top-10. If that happens we'll probably go LB - and get a guy like Maulauga, Laurinitis, or Currey if he falls to us, or less likely, a DT. I'd be shocked by anything else.