I never thought about this before. The Oregon runner was ruled down because his knee grazed the grass blades, but did not really touch the ground.
Reason this is important is the Oregon player kept running after his knee grazed the grass and then fumbled and PSU recovered. Replay overturned the fumble and called the Oregon player down instead. Then Oregon scores a TD on the next play.
Is the knee grazing the grass blades really considered down? I guess so.
