40 yard dash times are irrelevant...they don't run in pads or with a football for that matter. He can't however be that fast...his longest run last year was 27 yards...I think only 2 starting running backs had shorter long runs last year. One being Lamont Jordan.
He's a tough runner though, that's for sure...he rarely gets knocked on his ass. I always see him falling forward. Hopefully next year he'll get a little space to make a move or two, which wasn't really the case last year. But that game in Seattle where Bledsoe faked the qb/center exchange and threw to Willis...he looked pretty damn fast. I bet he's tears it up next year.