7–1–2–1 defense

The 7–1–2–1, or seven-diamond defense, used seven "down linemen", or players on the line of scrimmage at the time of the snap, one linebacker, two safeties relatively close to the line and one safety farther downfield. The formation was created by Minnesota coach Henry L. Williams in 1903, reputedly to stop Michigan back Willie Heston. By some accounts in the mid-1930s, the 7–1–2–1 was considered "almost obsolete" due to its weakness against the forward pass, whereas the 7–2–2 was still considered viable. Yet Bill Arnsparger notes the use of the seven-diamond from the 1940s into the 1960s, as a defensive adjustment to the common wide tackle 6 defenses of the time. Further, the form of the 7 diamond as derived from a wide tackle 6, with a more compact line spacing than the 1930s era 7 man lines, shows a marked similarity to the 46 defense of Buddy Ryan.

The 1906 football rule reforms mandated that offenses use at least seven down linemen. These players usually stood shoulder-to-shoulder before the snap, a posture defenses tended to match. The defenses of the time are considered unsophisticated by today's standards. The interior defensive linemen were expected to hold their ground against their assigned blockers, while the responsibility of disrupting the offense rested primarily with the tackles and ends, especially those lined up on the "strong" side of the opposing line.

Over time, however, as new offensive formations, such as the single wing, were introduced, and increased the lateral running and passing threats, the seven man front changed in character. Box and letter drawings of the seven man front, by coaches such as Bernie Bierman and Steve Owen show a broadly spread front, with the center and two guards versus the interior five offensive linemen, defensive tackles 2-5 yards from the guards, and ends 2-5 yards outside the defensive tackles, and well outside the offensive ends.

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