If you're an option coach sitting through yet another clinic lecture by some flexbone coach, you are likely to hear the following exchange:
Attendee: "Coach, why the flexbone? Why not split backs or the 'I'??"
Clinic Dude: "Why... so I can spread the defense and make them defend four verticals, of course."
Attendee: "Uh, Coach... how many times have you successfully ran four verticals?"
Clinic Dude: "Anyone have any more questions out there??"
Well, I finally found a clip of a good flexbone team running 4 verts(from GSU's first Natl. Championship game, no less)... a quarter roll left while looking off the Safety then hitting the right wing... Nice.