5. Costello ultimately proved to be the right choice at quarterback
The season began with Keller Chryst firmly entrenched at the top of the quarterback depth chart. Losing to USC was hardly a major blemish on his record, as Chryst threw for two touchdowns and didn’t toss an interception. 2017 might have transpired differently had Chryst remained healthy and on the field.
But an injury early in the UCLA game paved the way for K.J. Costello to take the field for the Cardinal. Costello led Stanford to victory against the Bruins, then followed up with another solid performance against Arizona State. Once Chryst was healthy again, the duo split time under center.
Then Stanford was forced to see how impactful having Bryce Love in the backfield was to their hopes of Pac-12 North contention. On a trip to Corvallis, Love left the game with an ankle injury. Without a strong ground game to back him up, Chryst faltered to a 16-of-33 performance with a touchdown and an interception against the Beavers.
Costello took over for the rest of the season. A loss to Washington State was a setback, but the redshirt freshman bounced back for three straight wins to close out the regular season. Against USC in the Pac-12 championship game, he acquitted himself well in defeat even as his completion rate dipped under 50 percent. Getting Costello meaningful reps this season sets up Stanford for a strong 2018 and beyond.