The 6-1 defense, is actually a variation of the common 4-3, and was a forbearer to the formation. The 4-3 defense is the most commonly used defensive formation by many teams in the National Football League.
Like the 4-3, the 6-1 alignment features four down lineman and three linebackers in the front seven. However, in the 6-1, two of the linebackers move up on the defensive line, which puts a total of six defenders on the line, with one defender behind the line in the box.
If you take a look at the illustration on the right, you will see a diagram outlining the 6-1 defense.
The Os in the diagram represent offensive players while the Xs represent the placement of the defensive players in the 6-1 formation.
Notice the lowest row of Xs on the line of scrimmage. You have two defensive tackles (DT) in the middle of the line and two defensive ends (DE) lined up just outside of the tackles. This is the regular appearance of a line. In the 6-1, the two outside linebackers move up so that they are lined up on the outside of the defensive ends. The remaining third linebacker lines up in the middle behind the line.
Two cornerbacks (CB), one on each side of the field, line up to cover the wide receivers, as usual. There are also two safeties that play deep in coverage. The exact position of the defensive backs (cornerbacks and safeties) depends on the scheme and the type of pass coverage they are in.
Early on in the NFL, teams commonly stacked their defensive lines with up to seven defensive linemen in order to prevent runs, which were heavily leaned on. However, as changes to the game began to favor forward passing, the defenses needed to evolve along with the offenses.
A variation of the 6-1 was initially employed by Head Coach Steven Owen and the New York Giants in 1950 as a way to neutralize the Cleveland Browns’ potent spread attack. The Browns, new to the NFL, had won multiple, consecutive championships in the All-American Football Conference, and had proven to be a force to be reckoned with.
The 6-1 defense is sometimes referred to as an “Umbrella” defense. The 6-1 Umbrella formation allows defenses to be flexible, as while it shows a six-man front, which is favorable to stop the rush, the defensive ends can also drop back into pass coverage if necessary. This defense helps to neutralize spread offenses.
On paper, the Umbrella appears to be a 6-1-4 defense prior to the snap, but once the ball is snapped, it can morph into something else entirely, such as a 4-3-4, or 5-2-4. The ability of the defensive ends in the scheme to flex into linebackers, dropping into short passing coverage, makes the formation especially adaptive and difficult to read for offenses. Prior to the snap, the quarterback might think that he will be facing a large rush, as there are six men on the line, and plan accordingly, but once the play starts, a couple of those men on the line could drop back into pass coverage, confusing the quarterback and potentially goading him into a mistake.