In 2017 if he'd lost to BYU but won another PAC 12 game it would have depended on which game. Beat USC or UW he's probably fine.
In 2016 again it would have mattered which game. CU, UW? Might have been fine. Beating Cal or Oregon wouldn't have made up for it.
In 2015 one more PAC 12 win of any sort puts us in the title game, so he'd have been fine.
In 2014 if we beat Arizona we're in the title game, so he'd have been fine. Other than that it's probably a wash.
In 2012 or 2013 he's in trouble regardless, but that's the 5-7 record more than losing/beating BYU.
In 2011 he's safe no matter what, but one more pac 12 win would also have put us in the title game that year.