The Cowboys barely have enough LBs to field a starting lineup.
Durant
McClain - You have to assume that he could flake out at any minute.
Wilber - He might have to play more DE than originally anticipated.
Hitchens - Probably not ready.
C. Lawrence - Really just a Special Teams player.
Carter - Probably a starter.
Your snapshot is pretty much on target.
Myself, I don't see Ronaldo McClain as a head case...only as a player getting back into the flow. He should prove solid in the middle, and I think healthy as well.
Hitchens just needs to grow, but he'll hit some bad habit times as he adjusts up in his intensities. He is a potential with heavy 'rookie' types of baggage.
Lawrence is a strong add for the special teams. Hey, that is an important area...but he does have a professional base line set of skills at linebacker. He will help carry some of the load for steady at the position.
Hitchens might just fit at strong side linebacker and make it work. I think his mixing into a defensive end position is too much to expect him to carry through the season as a steady duo job. His skills actually maximize in the role of linebacker...leave him there, except for isolated plays.
Carter has been paid for, and shown patience. It's now time for him to be pulling his yoke at the level of expectations...or simply, left to backup and waived at some point in the near future.
Durant is a good add on piece, but is getting old pretty fast now. Glad to have him for now.
This section badly needs Sean Lee right now...and another strong piece added.