Not all helmet hits are treated equally in college football. A case in point involved two hits in Stanford games in back-to-back weeks.
In the Central Florida game, Cardinal lineman Aziz Shittu was flagged for targeting, that is, bashing his helmet into running back Taj McGown in the first quarter. In addition to the 15-yard penalty, Shittu was ejected, leaving Stanford with only two reliable and healthy defensive linemen.
Had the play occurred in the second half, Shittu would have had to sit out the first half of the USC game. That would have presented Stanford with a big problem at a short-handed position.