Small and fast isn't necessarily the key to defending the spread IMO... It's using hybrid defenders. Basically a defense that needs 3, maybe 4, freaks. You need a Matt Wells that can be a S, NB, or LB, a McKinney that can be a LB or DE, a CJ that can be a DE or DT, and a Nick James that can dominate you at DT or truly be a NT in the 3-4.
Being multiple within personnel groupings without substitution = successfully defending the spread. The whole point in the hurry up is catching a team with an exploitable matchup on the field and then keeping them out there/not letting them sub that guy out. You don't have an exploitable matchup -- you can play the hurry up against itself. You confuse them with the different looks instead of letting them confuse you.
Oregon tried the "small and fast" thing on defense for a little while -- and then LSU happened. Look at them now -- sure not small anymore.
http://my.jetscreenshot.com/12222/m_...-uohk-40kb.jpg
Bielema is trying to run pro-style in a state that doesn't produce enough talent to do it like LSU and Bama do. He's a square peg in a round hole. I thought it was a head scratching hire at the time and still do. Time will tell for sure though.