I don't know what OU's excuse is but Navy's offense and taking the air out of the ball puts everyone on their heels and gives them a chance. Navy had the ball for almost 40 minutes of the game. All it takes is for Cincy to have 1-2 possessions where they don't score and Navy is able to stay in the game. Had Cincy not allowed the last minute score to bring it to 27-20, no one bats an eye over a 2 TD win.
OU simply didn't come to play as they assumed KU would roll over and play dead. They may be 8-0 but they're not anywhere close to being #3. OU now has close wins against 1-6 Tulane and 1-6 KU (and KU is winless against FBS teams since October 2019).