http://www.startribune.com/sports/vikin ... 70676.html
More at the link...When the Vikings play Cover 2, the middle linebacker is called the "middle-read" defender. He isn't asked to channel his inner Deion and run stride for stride with a wide receiver 30 yards downfield. It only looks that way sometimes.
"It's not like I'm flipping my hips [like a cornerback] and taking the guy man-to-man all over the field," Vikings strong-side linebacker Chad Greenway said. "If I was that fast, I'd be playing receiver."
With about an 8-yard head start, the middle-read defender drops as deep as the deepest receiver in his zone and simply tries to create a difficult angle for the quarterback. Only it's not that simple when you're 250 pounds or so.
"Basically, you're trying to buy air time on the pass," middle linebacker Jasper Brinkley said. "If the quarterback has to loft the ball over you rather than throw a line drive, that's air time for the safeties [who are playing two-deep coverage] to come make a play on the ball."