I, for one, don't think CJ is washed up by any means. It's very difficult to run the ball when your QB and OL aren't very good. He may not be the player he was in 2009, but if he comes here... he's going to start
you can't knock him for throwing screens, that's just a part of the system they run. they run a million and one tunnel/ bubble screens, try to tire out the d-line and then it opens up the run game which is also why Holgorsen, Leach, and those other Air Raid guys have had efficient rushing attacks.
what really has to impress you is his mastery of Holgorsen's offense... 3 to 4 read pass concepts, packaged plays, read routes... the kid has a high football IQ, just going to be an adjustment learning the offense... also i'm interested to see why the offense stalled second half of the year