I definitely believe he was a 1st round pick before he hurt his knee Saturday. I still don't think he makes it out of the top half of the 3rd round.
The upside with Carradine is tremendous. As good as he already is, he can be even better once he learns to play with better pad level instead of playing so upright all the time.
A lot of guys rack up what I call college sacks, but they don't necessarily translate to the NFL. Clemson in particular for example, has a long line of 'em from guys like Andre Branch, Daquan Bowers, Ricky Sapp, Phillip Merling, Gaines Adams, etc. You're not going to win in the NFL consistently with pure speed or a first move like you do in college.
Carradine gets NFL caliber sacks based on his ability to finish through incredible functional football strength in his core and upper body, and his ability to fight for hand position to disengage offensive tackles. Carradine has the ability to make an offensive tackle wrong even when he's done everything right. That's a rare quality, especially for a kid who's still playing with flawed technique.
That's also why he leads a defense full of kids who will be playing in the NFL soon in tackles from his DE spot, which is a fairly rare accomplishment.