McKnight walked onto the field at AT&T Park wearing a USC track suit and a backpack along with the rest of the USC tailbacks who were suited up for the game an hour before kickoff.
While rain poured down on the field, McKnight, wearing a beanie, paced around the field, and clapped his hands along with the position coaches.
Without McKnight, USC beat Boston College 24-13.
McKnight's alleged use of an SUV is under investigation by the school and a school official said the issue is still being monitored.
McKnight is USC's first 1,000-yard rusher since 2005, with 1,014 yards on 6.2 yards per carry and eight touchdowns during the team's worst season since 2001. The Trojans (8-4) failed to make a BCS bowl and win the Pac-10 title for the first time in eight years.
Arash Markazi is a writer and columnist for ESPNLosAngeles.com. The Associated Press contributed to this report.