For every pound that the Cowboys of the 70's lacked in weight compared to the current team, add it to their heart and love of the game. Many of them would have played for free.
The teams of the 70's played football. They would hardly recognize the game today with it's lopsided rules that favor offenses and handicap the defense. Today's football is half a game. With the exceptions of turnovers and sacks, fans hardly notice great defensive play. The only time a defensive name is called, it's for something negative and that is unbalanced.
The 70's teams didn't have "in the grasp" or "helmet to helmet" rules. The play was over when the QB was on the ground. They didn't have a no contact rule beyond five yards, receivers had to earn that catch. Roughing the passer? Only if the whistle had blown. Those are only a few differences.
And yet, there are far more game absences due to injury today than there ever was back in the 70's. Look back at the histories of these players. It wasn't unusual at all to find ten year careers in which they missed two or three games total.
The teams of the 70's didn't have players that had been trained at football summer camps since they were 8. They weren't administered selective, scientific diets that enhanced their abilities to get bigger and stronger. they didn't have personal, state-of-the-art weightlifting programs by experts who graduated from college with degrees in "Sports management".
How man fans today would have enjoyed the 6-2 score between the Cowboys and Browns in 1970 or the 5-0 score two weeks later in the playoffs? They were great! The Cowboys won both.
Please stop comparing today's NFL athletes to previous eras.-It's not relevant. It's not fair unless you acknowledge that the greatest difference between the two were the rules they had to play under. Do you really believe that guys like Romo, Brady, and Mahomes would survive a season if there was no such thing as "in the grasp"?
Again, I very much respect the dedication and skills of the football players today and I'm in no way belittling the intensity of their fan devotion. I'm just saying it was a different game played by a different kind of athlete back then.
A small story to add a little humor and take off a little of the edge:
Don Meredith, one of the toughest sons of a gun to ever put on a helmet, was playing with injured ribs. the team doctor had given him a protective jacket that was filled with a fluid that happened to be red in color.
On one particular play, Giant Hall of Famer LB Sam Huff hit Meredith so hard that he went instantly to the ground and the jacket ruptured. Huff was horrified to see all this red liquid oozing out of Meredith's chest. Meredeith looked up at Huff and said calmly, "Now look what you've done, Sam. You killed me!"