89 and 90 we won 10 and 8 respectively, but your point still stands.
Since joining the Big Ten in 1953 we've only had back-to-back winning records a few times.
1959-1960 (barely)
1963-1965 (3 year stretch)
1981-1985 (5 year stretch)
1989-1990
2010-2011 (barely)
If you use your 8 game win total or equivalent wining percentage for when they used to play fewer games, we're left with:
1963-1964
1983-1984
1989-1990
That is a SAD history. We've been bad since I can remember, (2001/2007 were the exceptions) but I always thought we had a pretty decent history. Looking at these records on sports-reference, that is not the case. We had a run with Butkus and a decent 10 year stretch in the 80s-90s; otherwise we've been bad.
Gives me an even great appreciation for this staff.