The NFL sure has changed over the course of the past 30 years or so. New Pittsburgh Steelers defensive line coach Karl Dunbar can attest to that. He was actually drafted by the team in the eighth round of the 1990s NFL Draft out of LSU (where he was coached by John Mitchell), though he did not make the roster (he later played a couple years elsewhere).
The game was far more run-oriented then, in part because of the talent that was available and in part because of the rules that were in place at the time.