I think the BYU fan assumption is that no one respects Utah therefore all ASU folks are indifferent with this game. That's not the case on the players and the coaches. These two have gone head to head back-to-back years in the standings and for top tier recruits. A lot of mud slinging back and forth, it boiled over quickly on the field.
Behind the scenes though, you're seeing a turf war for who's the second best program in the South.