Potential is just another way of saying the guy hasn't done anything yet.
That said, I think this offense could be very scary. The part that nobody here has been talking about (but I know we're all thinking) is how good our offensive line is going to be. We had 4 "2nd year guys" as starters last season, not counting Diaz (the Pitt transfer).
If Essington can improve his decision making (which by no means is terrible, just not awesome), and the pass defense/pass rush improves, a run in the playoffs is very possible.
You can't take anything for granted, but I think team could be something very special.