By the way, the story with the D2 defensive coordinator thing is that Al Johnson, former Badger star who was a GA alongside Fenelus at UW in 2016-17 got hired as the head coach at D2 East Central University in Oklahoma and brought Fenelus along as DC/DB coach. So it was a Badger adventure down there he got coaxed into.
It went okay, that was a down-on-its-luck school that Johnson rebuilt to some degree of success, and wound up becoming interim athletic director (you go down the divisions and it gets real fly-by-night real fast), but Johnson left this past season to go back to Wisconsin as RB coach (not sure if Fickell has retained him).
I would imagine both guys would say the experience taught them that Power Five football with its resources and structure is where they belong, but I'm sure they both learned a ton.