So, I don't have any experience in defending "wildcat" formations, but I did learn a little bit about defending the single wing and the flexbone. It utilizes wingbacks a "fullback" and has the option of having a quarterback on the field. Which the wildcat is nothing more than a derivative of. The premise of the flexbone is to set up the triple option and to makeup for a lack of a throwing qb. The single wing is more of a sweep heavy offense. What it ultimately boils down to is a lot of single-read options using a lot of motion with a direct snap to the tailback (or for the sake of formation-based nomenclature the fullback).
The bread and butter of this formation is a strong side single read option behind the backside guard on a pull. If the read is to the outside, the backside wingback takes the handoff from the fullback and his the edge ASAP. If the inside lane is there, the fullback keeps the ball and follows his pulling guard through the hole created by two downblocks on the play side of the formation.
In football, when you hear the phrase "the job of the runningback is to beat one guy" it is telling you there is a mismatch in personell. Typically, when the quarterback must deliver the ball to a specialist, the defense is playing 11, the offense 10. By putting the ball directly in the hands of a running back with the option running off of this gun-snap you force the defense to play you head up 11 on 11. If you execute your blocks, you can take advantage of this. If you put a non-mobile quarterback on the field (which has happened to me in college) you are coached to leave the qb alone unless you read pass block off of the linemen. The logic is that you regain a freed defender and restore the natural balance to the game. If you were to devote a guy to smacking the QB around, all you would do is waste a defender that could be better allocated. Not sure if this is how it is coached in the pros but in college this is how I gameplanned and those were the reads that I took while defending it from the inside linebacker position. Now that I got through with that rant, watch Bill talk about how important smothering the QB is...nothing like a hefty dose of e-embarassment!