The game is different these days but we shouldn't disregard the athletes from the past as inferior without fully understanding the changes.
We look at Payne Haas as a phenomenon these days because he plays 60 minutes as a front rower whilst most of the middles play just over 40 minutes. Back in 1979, they had no interchange and only two reserves. Forwards played the full 80 minutes as there were no strategic replacements in case an injury occurred.
There was no match review committee or bunker watching every play, and, as a result, the game was a much more violent version than what we have today.
In other words, the game was very much about attrition which would see opportunities open up for the elusive, fast players as the bigger men fatigued towards the end of the game.