Actually - it looks like he picked 8 games from 17 years where nebraska was ranked in the top ten and lost to unranked teams. There were others, 1976 #9 NU vs ISU comes to mind.
1972 opener- #1 NU lost to unranked UCLA.
1973 #10 NU tied unranked OK St- even a blowout loss that year 27-0 to OU.
1974 #4 NU lost to unranked Wisky also #5 NU lost to unranked Mizzou
1975- #2 NU blownout 35-10 by OU
1976- #1 NU tied unranked La Tech - #3 NU lost by 10 to Mizzou at home and lost to unranked ISU
More examples if you look.