Utah was #2 in the PAC12 in total and scoring defense. The award is not a national award. It's a PAC12 Award and I am comparing Utah's performance to Oregon's within the conference.
I think their defense was excellent for the most part this year. They finished 9-3 with one of the worst passing offenses I have ever seen. They faced 6 top-25 offenses in total yards. Hard not to call that successful.
And I am not taking anything away from BYU.