Get your cameras ready, I'm taking up the WIS side of things here...
This isn't really that big of a surprise. First of all, HD has more parity than real life, the gap between great teams and mediocre teams isn't as egregious as it is in real life. A lot of schools have a more equal chance of getting good players in HD as opposed to RL. Secondly, Air Force had lost 6 games prior, including a 10 point loss at 15-13 San Diego State (715 OTR, 98 RPI). The loss against Kent State was an 11 pointer on a neutral court (740 OTR, 82 RPI), thus it isn't really out of the question or out of the realm of reasonable possibility.
There are virtually no gimmes in the HD tournament, nor should there be. Its a different animal than RL and the talent disparity is much less in HD than RL...it would virtually be like that for any CBB game.