Before the late 1950s, almost all of the N.F.L.’s biggest stars played offense. Many teams never even introduced their defensive players before the game....Early in his career, Olsen was a devastating pass-rusher. His favorite move was the basic bull-rush. He would pound and pound on a usually smaller guard, then supplement it with an additional tactic not available to today’s pass rushers: the head-slap. I even remember him occasionally using the double head-slap.