Dez is largely a product of Tony Romo. He runs three routes and has average speed, but Romo knew how to use it. Those back shoulder throws were indefensible, and Romo knew how to buy time so Dez could run around and freelance. That's gone.
Same can be said for Miles Austin, Laurent Robinson, Terrance Williams, Patrick Crayton, and Sam Hurd. Average dudes who got big paychecks, then went and did absolutely nothing elsewhere without Romo.
Dez is good, but he's not great without Romo. That's proven.