I'd consider "big games" as prominent major matchups, like against top 10 caliber opponents, big road games or obviously NY6/BCS/CFP games.
2010: vs. Stanford (L 14-37)
2011: @ Michigan (L 31-35), vs. USC (L 17-31), @ Stanford (L 14-28)
2012: vs. Stanford (W 20-13), @ Oklahoma (W 30-13), vs...