This is a very depressing way to look at things, but its tought to argue. Each of the last 3 seasons I'm convinced we were 1/2 quality defensive linemen away from being 9-11 win teams all three years. Our offense has put up huge numbers since CPJ came (easily number 1 in the ACC in total offense and PPG if you average all 5 years).
The horrid '08, '10, and '11 DL classes are (IMHO) the reason CPJ isn't a 50 game winner over his first 5 seasons. We've had some alarmingly bad DLs since the '08 foursome.
How much of a difference did Derrick Morgan make?
I don't think it's depressing--think of it this way: we're a player or two away. As opposed to teams that have plenty of talent, and just can't win.