Toughest opponents averaging 70% completion and 300 yds/game. Arizona is rankes 43rd in pass yds /game. Wisconsin and cal are schemed towards the run so it makes sense that their passing o isn't as high as others. Wisconsin completes a high percentage of passes making them a very efficient passing offense
Looking at efficiencies (which accounts for SOS and garbage time) in all three facets of the game shows that usu has a better offensive efficiency and byu has a much better defensive and special teams efficiency. Air force and NMSU have horrible offensive efficiencies, with msu being decent (still putting up 38 on usu). BYU hasn't played the most efficient offensive teams, but better than usu's.
Your argument against wyoming could be the exact argument used against Utah state, maybe more so against usu.