This is my take on the RB class.
Davis (Clemson) - Best pure runner in the class, but he can't catch a lick.
Wells (OSU) - soft runner that doesn't finish. I have doubts about him.
Moreno (UGA)- Very nice runner with a bit of cut back ability. very poor blocker.
Ringer (Mich St.)- Ran well to the outside last year, how does he do in the middle without Caucick this year.
MCCoy (Pitt) - Barring injuries destined to be the best pro of this group.
Johnson (Boise St.) - how fast is he really vs. how slow he looks while playing.
Lucky, Devine, Unga, Murray - A notch or two below the ones listed above.
Two you left off the list are Harvin of Florida. Best playmaker in this group, hands down. Can he run inside and can he learn to block. And Spiller of Clemson. Super speed, super speed and more speed. First step is lethal and the second step is usually as he blows by you.
I would take Spiller or Harvin over any of the others listed above, if I had a true #1 back, like Maroney, on my roster.