bulk of them on pass plays. Outside of that BYU averaged 2.4 YPC. You do make a good point that both teams will have different running backs featured this year, but based on all the stats at hand you'd have to agree that it's unlikely to expect BYU's run game to outperform what Utah allows on average by a significant amount. 3.3 YPC no matter how you try to spin it isn't good. Even though that was better than what Utah gave up on average, it would not be considered "faring well". Similarly Utah was .3 YPC below their average as you shared with backup RBs and QB. Even then, if you're getting over 4 ypc, you're moving the ball pretty well.

Utah doesn't have a severe lack of experience at LB. Manny Bowen has a good shot at getting drafted next year and played 30 games at Penn State before coming to Utah and has been with the team for a year. The other starting LB, Francis Bernard, played 12 games last year for Utah and 12 at LB for BYU. Last year he had 5 TFL which is more than every returning defensive player for BYU besides I. Kaufusi. 54 combined games for a starting LB duo is pretty good. Those 2 players have more combined games than BYU's top 5 LBs heading into the season. 

Bringing back 3 starters on the OL is pretty good and Utah has never been worse than average on the OL no matter how much turnover they've had. BYU bringing back most of their DL is good and bad. Having cohesion is great but if the same unit that was already bad at getting into the backfield brings back everyone except their best player you have to be careful with your optimism. BYU has no proven disruptive player on the edge and there's no reason to expect drastic improvement at this point. BYU's DL is tough in the middle but overall the DL isn't going to be getting into the backfield much, and that's the number 1 thing an OL is worrying about. Heck, Utah averaged over 4 ypc last year and put up 28 points with backup RBs and QB and BYU's returning defensive players only accounted for 2 negative plays. The more I look at this the more I want to give Utah the edge, but I'll still say a wash between Utah's OL and BYU's DL.  

Overall, if you're being objective I don't think you can say that BYU's OL has an advantage against Utah's DL or D as a whole, when it's considered one of the best DLs and defenses in the country with zero players lost. There's not an OL that Utah will face all season that will have an advantage at the line against Utah.