With all due respect to the mighty Hub Blog, the big fatties are not the cause of the most severe injuries, especially head injuries. It is the guys who are flying around the field, with speed and power, who have room to move and accelerate. Who are the most fearsome hitters in football...not usually the fatties up front. These days, it's the safeties and linebackers. The biggest hitter in the Super Bowl this Sunday? It's Steelers safety Ryan Clark, who stands all of 5'11 and weighs 205. Rodney Harrison, Ronnie Lott, Jack Tatum -- all relatively small guys in the secondary.

We need much stricter enforcement of the rules, severe punishment for headhunting, leading with helmet, etc. One of these days, we'll see a player killed on the field, it's inevitable.

Since you bring up physics....yes, weight does matter, but Kevin is correct. It's the guys flying around the field who create the most risk. Why? Well, remember that force is mass times acceleration (which is velocity squared). Ergo, a 240 pound linebacker who moves far more quickly than a 325 pound lineman will create more destructive force.

A huge lineman is still a danger, if for no other reason than when he meets a 235 pound halfback running at full speed, the force has to go somewhere. But, he's not generating it himself.

Maybe HubBlog could call in an expert on physics. I, too, think speed plays a bigger factor than weight when it comes to head injuries. The bigger guys may hurt more when they land on you, but they aren’t able to get going fast enough to do as much damage as the missiles coming from the safety or linebacker positions. When two decent sized and speedy players get together (receivers,/running backs v safeties/linebackers) that’s when the real damage gets done.
Another note in defense of the big guys: they aren’t all fat. There are some 6’6” 330lb guys that are in better shape than some of the 280 lb guys from the good old days. Not all, but in general, I’d say the players are healthier now. They work out much more in the offseason, they rely on nutrition and weightlifting to put on good weight. Equipment and surgery, too, have come a long way to reducing the severity and permanence of injuries, I’d guess.

On top of it all, football is so much more popular and sophisticated now than it was years ago. Their stealing some of the better athletes that might have played another sport in generations past. To me, that means more competition among better, fitter atheletes.