Eh.
I don't know. Bill gets a pass for the 5-6 year. He inherited a bare cupboard. Never mind the previous record, we all know what kind of talent Frank left Bill versus what kind of talent Bill left Bo (in case it needs rehashing, maybe a list of current Huskers in the NFL would suffice).
Obviously, in 2007, the team collapsed. Not a pass, but a failure and the reason why he's gone.
Collapse aside, 8-4, 9-5, borderline or second-tier Top 25 products, that's where we were then and it's where we are now. The difference between then and now is Bo a) didn't have to rebuild, b) hasn't yet suffered a season collapse.
If Callahan was really fielding a consistently just-shy-of-7 wins a year team that the 27-22 would suggest on average, that's a different story, and I'd agree: a clear step below where we are now.