Not sure what Utah's schedule has to do with the effectiveness of Tuiaki's Defense... but, since you went there,
here are some additional facts:
BYU has scored 277 points this year.
BYU's opponents have scored 256.
That's an average of 27.7 PF, per game, and 25.6 PA, per game. BYU's average point differential +2.1 points per game.
That's not horrible. It's not great, but it's okay. BYU's record includes 4 P5 opponents. The two wins vs. P5 opponents came in overtime, and the two non-P5 losses were one-score games. BYU got spanked by Washington and Utah, but also spanked Utah State and Idaho State.
"Utah only has two good wins- UW and BYU." Okay. That's awesome. BYU has more "good wins".
Utah has scored 347 points this year.
They've held their opponents to 113 points.
That's a point differential of 234, or average differential of 23.4 ppg.
They also have the best rushing defense in the country. They're also ranked in the Top 5 of multiple other categories- including scoring defense.
I'm honestly not sure WHY so many people like to point out about the SOS. No team can do anything about whether the rest of their conference sucks. They CAN control their OOC schedule, which it looks like they're trying to do in the next few years. Nevertheless, despite their weak schedule, they're #7 in the country.
Utah is the best team BYU has played this year. Washington is #2. Utah beat BYU 30 to 12. UW beat BYU 45 to 19. But Utah also beat UW.
I LOVE that BYU schedules tough opponents, but it would make me a lot happier, and matter a WHOLE lot more- if they actually beat most of their tough opponents- and destroy ALL of their G5 opponents.