The answer is simple, New Mexico. New Mexico has a lot returning players, and they were good last year. I expect a better New Mexico team in 2016.
New Mexico's 2016 schedule breakdown
New Mexico's non-conference schedule:
South Dakota, at New Mexico State, at Rutgers, and ULM
All of these games are very winnable for New Mexico. Rutgers is the only one should prove to be any level difficulty, but New Mexico should win this game.
Rutgers in 2015 went 4-8 and 1-7 in Big 10 conference play.
New Mexico's MWC home schedule:
Boise State, San Jose State, Nevada, and Wyoming
All of these games are winnable for New Mexico. The most difficult team should be Boise State, and New Mexico beat Boise State in Boise, last season.
New Mexico's MWC road schedule:
Hawaii, Air Force, Utah State, and Colorado State
All of these games are winnable for New Mexico. The most difficult team should be Utah State, and New Mexico at home beat Utah State by one point, last season.