If the players today are in so much better physical shape then how come injuries are more frequent?
Keep in mind that there have been extensive rule changes since the 70's for the express purpose of preventing injuries.
DT Jetrhro Pugh started for 12 consecutive seasons, missed 12 games and some of them were the last game of the season when they had already clinched top seed.
LB Lee Roy Jordan, 11 consecutive seasons, didn't miss a single game.
LB Chuck Howley, 11 seasons, missed 7 games.
LB Dave Edwards, 13 seasons, missed one game.
HOFer DT Bob Lilly......13 seasons, didn't miss a single game....not one.
DE George Andrie, ten seasons, missed one game.
These guys were six of the front seven of the Cowboys starting defense that won their first Super Bowl in 1971.
Do you know who their backups were? I don't. Depth was irrelevant but they were there.
Dave Edward's backup was D.D. Lewis. He started two games in his first three seasons. Then after Edwards retired, Lewis started for 9 seasons, missed two games.
These guys didn't have "programs" to keep them in the top physical shape, yet their durability cannot be matched by today's NFL player.
There has been rule changes but the game hasn't really changed that much. It is still football. What the teams of the 70's lacked in physical perfection, they made up for in mental toughness.