OU 56, BYU 21
On defense, I think BYU will be fortunate to hold OU under 50. I have a hard time believing that BYU's defense is better than Texas Tech or Missouri or Oklahoma St who all gave up 60+. BYU's defense at the end of last year could have given up 100.
On offense I expect BYU to struggle with the loss of Collie and the oline. I expect the OU defense to come out motivated and for BYU to give the away repeatedly.
To be honest, I think the final score will be more like 73-10. I'm afraid BYU is at Stoops mercy and he's destroyed some great teams in the past.