Less proven. Well, I suppose that only playing one year versus 7 or 8 qualifies as less proven, but it's not like the guy didn't just win the Super Bowl or anything. Hardly an equivalent comparison.
Had WM ever touched the ball even once for a single carry in a real game prior to the draft, then you may be getting a little closer. Had WM proven that he can carry the ball for even one complete game, then perhaps. It's more like, had WM carried the load as a starter to show that not only can his knee survive, but that he can be a successful starting RB in the NFL, then you're right about near the same comparison.
Oh wait, that's where we are right now. Not last year.