Mandel correctly points out that NU only defeated one BCS conference opponent with a winning record last season...in the regular season. He also ignores the progress the defense (and in fact the entire program) from the start of last season to the end of the season.
Mandel also makes the sin of confusing continued improvement to being on the "brink of returning to glory." Nebraska's not there, and winning the Big XII North doesn't mean "Nebraska's back" unless you lower your interpretation of what "glory" means for NU.the regular season. He ignores the progress during the season and how the defense improved from the start of the season to the end of the season.
Of course, Mandel further hurts his credibility by talking to Minnesota co-defensive coordinator Kevin Cosgrove at the start of his column for insight on how to prepare for opponents. Unless by preparation, he means practicing defending extra points and returning kickoffs.