Stanford tried alternating quarterbacks during a series in the second quarter Saturday, but the offense succeeded mainly in moving backward. Burns returned and had a short run, but the play was nullified by a holding call on fullback Chris Harrell. When Stanford finally got off the play, Burns was sacked and fumbled, although Stanford tackle Casey Tucker fell on the football. Head coach David Shaw disputed a reporter’s contention that the offense looked confused. Thomas had blood on his face after a play on which he caused Colorado’s Sefo Liufau to hurry an incomplete pass. A Buffs lineman was called for illegal hands to the face after taking Thomas’ helmet off. Cornerback Alijah Holder returned after missing three games with a shoulder injury but reinjured it early in the second half.