Yep. All those greats from back then would barely make it today. Just watch a tape from a game in the 60's-70's. They're slower and smaller. Today's defensive ends are faster than running back's were back then. Today's lineman outweigh those guys by 60+lbs. Just looked up Conrad Dobbler's stats, sure he was big at 6'3" 250ish pounds. But Derick Henry is a running back and almost that size. It wouldn't even be a fair matchup. The big bad Jack Lambert was only 220lbs during his days on the Steelers. There are receivers bigger than that now.The men back then would be dominated by the men playing today. The athletes today are bigger, stronger and faster, that's a fact.
Those guys back then couldn't hang today on their best day.