CU may be a hibernating giant, but they are far from a dumpster fire. If they're willing to seriously commit to football success aGAIN, they'll improve rather quickly.
As an MSU and CU grad, I can tell you that CU right now is the epitome of a dumpster fire: outdated facilities, an apathetic fanbase, an LT-like figure in athletic director Mike Bohn, very few D1 quality recruits in state and a town that does not support college football. They have not put out a good product in YEARS, and our Croom three-win teams would have beaten CU's last two teams handily.
Twenty years ago, I would have told you that CU was a significant step up for a coach from MSU, but the tables have clearly turned the opposite way. I think we're finally learning how to build a football program, and CU's has been virtually ignored since the McCartney days. They had some good years under Gary Barnett, but Barnett's ways eroded a lot of the local support, and Dan Hawkins and Jon Embree were jokes.
I don't see Mullen leaving the SEC for CU. They'll get someone with California ties.