re: #150 erik_t
The style of the game is very different. Rugby players tend to concentrate in the scrum, and high-speed collisions are rare.
Blindsided quarterbacks and slot receivers annihilated over the middle are the real concussion causes, not the linemen pushing against each other.
See also: leaving the feet and leading with the head. You see concussions in hockey, but a lot less than in football. And you’re landing on ice in hockey.