this was a part of a good CSC take on GW. Thought it deserved it's own thread to make sure everyone gets up to par on the GW 46 variations-

In short, it's a 46 defense also known originally as the Bear 46. It was created by Buddy Ryan while he was the defensive coordinator for the Chicago Bears and the name comes not from any formation but from Bears safety Doug Plank's jersey number. Here is the basic theme behind it.

The "46" was an innovative defense with a unique defensive front; designed to confuse the quarterback. The line was shifted dramatically to the weak side (opposite the Tight End), with both Offensive Guards and the Center "covered" by the Left Defensive End and both Defensive Tackles. This front forced offenses to immediately account for the defenders directly lined up in front of them, making it considerably harder to execute blocking assignments such as pulling, trapping, and in general, pass protection. Moreover, the Right Defensive End would align outside of the Left Offensive Tackle, leaving him "on an island" when trying to block him.
Another key feature of the "46" is that both outside linebackers play on the same side of the formation. To avoid confusion the strong side linebacker (who is no longer lining up on the strong side) is frequently renamed to the Jack Linebacker. The linebackers line up behind the linemen two or three yards from the line of scrimmage. The primary tactic is to rush five to eight players on each play, either to get to the quarterback quickly or disrupt running plays.
At it's most basic form, this is what the base "46" formation looks like.

Defensive Line: The "46" requires a lot of pressure from the front four, particularly the defensive ends. Pressure is constantly being applied from the outside and a lot is required from the two end positions.

Linebackers: The outside linebackers play just off the line of scrimmage acting basically as two extra down lineman. The middle linebacker is also in the box next to the strong safety.

Safeties: The strong safety is so far up that he is essentially a fourth linebacker. He has the option of blitzing or dropping back, always leaving defenses questioning. The free safety is left alone in the backfield for cover help.

Cornerbacks: The cornerbacks are responsible for playing tight man-to-man so they must have great coverage ability because safety help is minimal and limited to only the lone free safety in the middle of the field.

We all know Williams is a tough guy off the field and that attitude will definitely show through in his defense. The main objective of the "46" is attack, attack, attack the pass protection from all angles in an effort to shutdown the quarterback. With eight men in the box, pressure can come from anywhere; from all eight men to simply the front four and anywhere in between. The trick is constantly mixing up the pressure packages and formations in an effort to test the opposing offense and look for weaknesses to exploit later in the game. It's also meant to always keep the offense guessing where pressure will come from next. This is an inheritently aggressive defense built around a lot of blitzing. And blitz Williams will do. This is no secret. He told us so when he first arrived here in New Orleans.

"You've got to be excited about the offense," Williams said. "... If you like to (play) pressure defense like I do, then you get a chance to pin your ears back and rush the passer more when you can put points on the board."

But don't expect the defense to look exactly like this. It would be considered a bit unusual in today's NFL and after Bill Walsh developed the West Coast Offense to exploit the "46", too many teams now can easily take advantage of the traditional formation. It is more likely that the Saints will use the basic philosophy behind the "46" but in an adjusted version that will probably look more like the traditional 4-3 with lots of different pressure packages.