Notre Dame starting CB and former Michigan target Lo Wood tore his Achilles and is out for the season. Notre Dame's secondary was their weakest unit and biggest concern entering the season as they graduated 3 of their starters from last year (Robert Blanton, Gary Gray, & Harrison Smith) and lost out on their star CB recruits from the 2012 class (Ronald Darby & Tee Shepard).
Which leaves them with this:
Without a healthy Lo Wood, Notre Dame has two scholarship cornerbacks who were actually recruited to play cornerback. Two.