FinAtic8480
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In fact, it was the 1972 Miami Dolphin team that was the first really successful NFL team to run a 3-4 defense. At that time, most teams were using the 5-2 or a “modern” innovation brought to the league by then Defensive Coordinator for the NY Giants, Tom Landry, the 4-3. This was in the late 1950’s and early 1960’s.
Coach Shula knew Defense
But Don Shula knew that this was to be the great successful defense that would win championships. And he ran this defense throughout his tenure as coach of the Dolphins with Bill Arnsparger as his Defensive Coordinator.
http://phinphanatic.com/2010/07/07/dolphin-3-4-defense/