Because BYU won 2 Big 12 games this year. If you want to be bowl eligible, you have to have some easy wins.
I follow Maryland football because I live next door. They regularly struggle to get 6 wins. This year they managed to eek out 7. Winning those first 3 non-conference games is critical, because they have to play Penn State, Michigan, and Ohio State every year. That means they have to go .500 with their remaining Big 10 schedule to get to bowl eligibility. That includes teams like Nebraska, Iowa, Michigan State that can be tough games in a given year.