Frankly, this whole southern speed concept has little to do with position players. Ted Ginn is as fast at Ohio State as he would be at Florida. The term "southern speed" contemplates a concept of "team speed" essentially meaning that the "big fellas" play faster... Or, in other words, Big Ten Teams bulk up to better run block - and Big 10 D's bulk up to better stop the inside game.
Of course, all this is complete crap. In the 1998 Sugar it was clear Florida State had much more "speed" than OSU where the lines were concerned. OSU, at the time, was a more typical grind it out on the ground team (notwithstanding the fact that OSU had some great Wideouts and Corners and "speed" guys) What changed, however, is that sometime around then, maybe a little later... OSU decided, hey, wait a second... Flast may be on to something... they're keeping their lines fresh and playing "faster" and they were throwing my QB around like a rag-doll. Well, now some 8 years later, OSU is just as fast as any otehr team. Now, there are some teams, like Wisconsin or Minnesota for example, who still seem to champion bulk over speed. And, as a general matter, South East teams champion speed over bulk.
It's just the way the game has evolved, and I'll admit southern teams were the "first" to take that tact successfully. Lets not forget, in the 1970's damn near every team worth half it's salt was running the option. Speed - as I've outlined it above - wasn't a factor then...