A reader writes:

Your reader makes a good point about the fact that brain fractures and resulting death have decreased as helmet technology has progressed, but at the same time brain injuries in general have gone up.  This is because as they make the helmet "safer" for the people wearing it, they are also making it more dangerous for those it is being used against.  Helmets used to be made of leather, which is not exactly a lethal material, but today’s football helmets are like weapons.  Almost all head injuries in football, in fact, occur due to "helmet-to-helmet" contact.  In my opinion, it might not be a bad idea to get rid of helmets altogether, as that would probably discourage a defensive player from throwing his head full force into an offensive player’s left temple.

Another adds, "One of the things that NFL Commissioner Roger Goodell is going to have to address is that tacking without extending your arms will draw a 15 yard penalty." Another reader:

I have also encountered speculation that helmet design is making things worse. 

The guesstimating runs this way: as the helmets become ever more able to cushion physical shocks to the head it becomes ever more possible for the shocks to become stronger, and along with that the shocks not severe enough to cause a player to be knocked unconscious (stopping the game) but still severe enough to cause long-term degenerative damage become more frequent. 

If this hypothesis turns out to be true, then it would have been better for football to have adopted rugby's no-helmet uniform.  Rugby has lots of players with misshapen noses thanks to the battering those noses take on the field, but to the best of my extremely limited knowledge rugby doesn't have a history of players with long-term brain injuries and progressive neurological degeneration caused by collisions on the field of play.

A reader with more experience agrees:

As an American who has played rugby for over ten years, let me offer an explanation of why football players suffer so many head injuries: it's the helmets. Because American football players wear helmets (and pads), they are not taught to tackle correctly; they use their heads as battering rams, instead of protecting them as they should. American kids, especially in high school, are not taught proper tackling technique, but in a way that gives the "big hit" the fans love and the helmets fail to guard against. But ruggers are taught to wrap the man they are tackling, placing their head on the side away from the ground, and using the body of the man they are tackling to lessen their impact on the ground. They are taught to tackle with their heads.

While head injuries do occur in rugby, they are the result of failure to tackle correctly; head injuries in the NFL result from tackling just like they teach you to. In every season I've played and coached rugby in the US, I've had to spend time teaching guys who had played American football the basics of safe tackling. They simply didn't know how. It was always a race to teach safe tackling before they injured themselves, or someone else, in practice. The best thing American football could do to deal with this issue is import rugby coaches to teach American football coaches the basics of safe tackling.