In the P12, Utah has to win the P12 CCG to make an NY6. Realistically, they probably would have to go 9-3 or 10-2 to make it, and against very hard competition. Being that last year was a down year for USC, UCLA, and Stanford, the chances of doing that well are slim.
In the MWC, they would have to go undefeated, but really the hardest game would be against Boise St. There are more than a few gimme games. It is tough to run the table in the MWC, but doable.
So, it is a little counter-intuitive, but it is easier to go to an NY6 in the MWC (because you're pretty much playing down a league and it's easier to run the table).
Of course, you're never going to make the CFP in the MWC.