The NFL is a much tougher sport now than it has ever been. The only position that's not true for is quarterbacks and only because they get the benefit of a rules set not available to other players.
Ehh, I don't know. The players are bigger and stronger now, so the collisions are tougher, but in many ways the sport is easier and safer these days. Wide receivers don't get mugged all over the field anymore and that was before they had a pass thrown to them. Many times they would be clotheslined after catching passes. The fields are in much better shape in this era. That helps all the players, especially running backs. No more quick cutting and no more getting tackled on those old school artificial surfaces that were hard like a rug over concrete.
