2018- Boise by 5
2017- Boise by 17
2016- Boise by 1
2015- BYU by 9
2014- Boise by 25 (okay, that one wasn't competitive)
2013- BYU by 17
2012- Boise by 1
That's 7 games with 4 very close games (the 2015 game was the pick 6 game, right?). Sure, 17, 14, and 13 weren't super close in the final, but for the most part the games have been pretty competitive. I don't know anything about those three games, so they might have been close early and gotten out of hand late, which would support your point.