Today, the Iowa Hawkeyes defeated the Nebraska Cornhuskers, 28-21. The result is that Nebraska wound up with a 1-8 record in Big Ten conference play, with 239 points scored and 239 conceded. This was largely due to a 56-7 win over Northwestern and a string of close losses, and it seems extremely hard to repeat under most any circumstances. Many stat-gazers were upset Nebraska did not hold a 21-6 lead, so they could've been 2-7 with a positive point differential.
But this seems like it's probably happened before. I wondered what are examples of extreme unexpected win/loss differential, at any level of American football? I'm looking for conference records or overall record (Nebraska's overall record was 3-9, with a net positive score) for NFL, NCAA FBS/1-a, FCS-1aa, etc.
When I say differential, I mean examples where it is flipped: highest net-win differential with negative points. For instance, a 7-2 team with a net point differential of -3 would count as much as a 7-2 team with a net point differential of -45, which would count as much as a 2-7 team with a net point differential of 21.
This question isn't restricted to end-of-season records, but I figure they're easier to look up.