Its tough to say, because how much does coaching factor in? I know this might be triggering, but I'm gonna zag and say Frost. Only slightly compared to Rhule though, so hear me out guys, Im just hear for the debate. It was trash when Frost got it and also trash when Rhule got it, not trying to be a defender, just trying to have a good ole message board debate.
Defense - Frost is unquestionably worse IMO
The defense was turrible in 2017 and going into 2018. No linebackers to speak of, secondary was sparse, and the DL had some guys that would turn out to be okay, but they were built for the 4-3 compared to the 3-4. The were getting routinely ran over until about 2020
In comparison, I think Nebraska defense for next has the opportunity to be a solid defense.
Offense - Rhule is worse. But here is where I have trouble, does Martinez count as where Riley left it, because Frost picked him up. If we are running an offense with Andew Bunch and 175lb Gebbia how good is it? SAme with Mo Washington as he was a big weapon that year. RB - Ozigbo was an after thought going into 2018. Does get credit there? But we had a solid OL, 2 great WRs. Lacked a lot of depth though IMO.
Anyways, I think Nebraska should have been about 6-6 to 7-5 in 2018 if Frost was a competent coach.
Still a lot to be decided but I think Nebraska has the opportunity to go 6-6 to 8-4 next year. Maybe I'm crazy.