There is one position, though, that, when given a little twist, can make the entire defense come alive.
"In Coach E's defense," explained outside linebackers coach A.C. Carter, "in this 3-4 style of defense, you need someone that can change the math of the game."
Essentially, by allowing one of the outside linebackers/edge rushers to become a hybrid backer—playing as a pass-rusher, run stopper, or coverage guy from snap to snap based on his own diagnosis of what is happening before, during, and after the snap—you can turn a 3-4 into a variety of different looks, or "change the math," to use Carter's term.
Football is a numbers game, a puzzle where certain pieces fit, and whichever side can arrange them the quickest and in the correct sequential order often wins the play. Having a dynamic hybrid linebacker allows the defense to manipulate what the offense thinks they're seeing. They can't plan for that player because the player himself can change his role mid-snap.