I do disagree with some CBers that claim that BYU was head and shoulders the better team in 2012 and 2013.
In 2012 I think both teams were pretty mediocre and about even.
Last year I thought that Utah had a slightly better team. BYU was able to pad their wins against weak teams and anytime they played a decent team they lost by double digits (note the Bowl game against the 6th best PAC12 team Washington). I am pretty confident if BYU had to play Utah's schedule last year they wouldn't have won more than 5 games either.
This year I think the talent disparity really showed. Utah suffered a lot of season ending injuries just like BYU and was able to have the depth to still win 9 games.
We'll see if the trend continues or if this is one of those cyclical things.