Having high expectations dashed makes for a bad year that can be exacerbated by losing to one's main rival and having frustrating coaching decisions. I'd argue that having a rash of injuries a la Wisconsin is different, that is a legit excuse, and "we'll be back".
Some candidates for this award:
Auburn - top ten initial ranking and lost to LSU and Bama and UGA and Tenn. Not a good year.
Michigan - a pretty good year by normal standards, but after the loss in week one looked really good on defense until ....
Wazzu - kind of the same story in a way, a great year turned south by the late loss to rival
Miami - high expectations again and now frustration with the HC and a mediocre outcome in a weak conference
Alabama - well, just because they allowed some points to be scored, their fan base is only happy for about five minutes a year
Kentucky - another story of having a very nice year spoiled late
UCF? - undefeated season, again, and no CFP sniff, plus injury to QB
Contingent bad years:
ND - IFF they get torched in a playoff game
Clemson - ditto
Florida - if they lose to UCF
Tennessee - if they lose their bowl game, oh wait.