The only situation I can think of that went a little like that was Howard Schnellenberger who built a monster at Miami, won a National Championship and then left.
He took a year off and went to Louisville. 5 losing seasons in 10 years.
I thought he was a B until I started meeting some of his players. Then moved him up to an A-. Very impressed with the way they conduct themselves in public.
The only blemish he has IMO is not winning the West. Once Wisconsin started their descent in 2020 it was there for the taking each year.
If I was Ohio State's AD I haul ass to the Fox announcers booth & wouldn't let Meyer leave the stadium today until they have a deal in place for him to take over and coach the team in 3 weeks.
They gave up over 5 yards a play on the season. That's only happened twice since Parker took over at DC and not since 2014. Easily their worst defense in a decade.