http://www.philadelphiaeagles.com/ne...b-a87a3614f793
"When you study a Mike Zimmer defense, you see a lot of the same hallmarks of Johnson’s scheme. With Zimmer, the head coach of the Minnesota Vikings, it all starts with their aggressive pressure package. The foundation of what they do is based on what is termed as A-gap pressure, which is basically attacking a quarterback right up the middle. A gaps are the two spaces directly to the left and right of the center, between the two guards. The reason for this is simple, the A gaps provide the shortest path to the quarterback. By constantly threatening that space, Zimmer’s teams are always aiming to be in a quarterback’s face and disrupting the action."