Mark Rippetoe describes the angle of the barbell needing to bisect the exact middle of the foot in both low bar backsquats and front squats. I have to disagree with the "ball of the foot" thing with regards to any squat lift; if you're centering the barbell over the front of the foot, in my own humble opinion you're doing it wrong. Bar should basically be bisecting your shoe laces.
One thing that has been abandoned over the years in football strength training is the standing overhead press. The bench press has replaced it in importance which to me is one really disappointing factor. Think about a lineman's body position as he's gaining leverage and leaning forward; if only the bench press is done in the weight room, the shoulders/triceps are neglected in favor of more biceps-centric training. I wonder if Duvall does the overhead press with the guys, I'm interested in that.
This is just gym nerd theory stuff though. I'm not taking it all that seriously one way or the other.