Nick Saban, among others, is suggesting that hurry-up offenses (like the one Auburn and Florida have used to beat his team is recent years) are dangerous to those poor defensive players who just never get a chance to catch their breath. And apparently the pocket-protector and white-lab-coat nerds agree. That settles it: no more hurry-up offenses. Let's just line everybody up and have them smash into each other 120 times a game.
What complete nonsense!
Clearly, Saban has a profound conflict of interest, here, but leaving that aside does the logic of his claim hold up? Of course not. The proper response, if your 320-lb defensive linemen can't keep the pace, is to recruit smaller linemen. Linemen who can keep up with a fast-paced offense. This would have the effect of reducing the difference in momentum between offensive and defensive players, thereby reducing -- not increasing -- the risk of the most serious, head injuries. (There's some subtlety in the trade-off between momentum and energy, but I think momentum is the big issue, as I explain below.)
Furthermore, most of the fast-paced offenses run a lot of East-West plays -- runs designed to attack the edges of the defense and exploit cutbacks. In these plays, the offensive and defensive players are usually running obliquely rather than right at each other. Compare an inside linebacker taking on a fullback head on in a power play versus fighting through the second-level block of the tackle to reach a back running at an angle away from him. I have no data on this, but I bet the cumulative impact on players' heads is lower when they run hurry-up (i.e., spread and read-option) even though they run more plays.
At the very least, I think we can conclude that Saban is talking out of his... trunk.