As training camp begins, the defense is where the real questions reside. It appears that rookie Nate Allen can emerge as the starting free safety, a position that has been handed around often since the departure of Brian Dawkins. Who will start at cornerback opposite Asante Samuel and who will be the regular nickel back is an open question. How the defensive-line rotation will work with rookie Brandon Graham in the mix will be interesting. And how the revamped linebacking corps shakes out is still a mystery. There certainly are a bunch of linebackers on the camp roster, and McDermott might shuffle them again and again before finally having to discard.