Trying to rank running backs is just ridiculous, and it's certainly the one position where you can't base things on statistics. If an offensive line doesn't create any holes, the best RB in the history of the NFL couldn't pick up 4.0 yards per carry. On the flip side, an O-line that does nothing but create monstrous holes can turn a horrible RB into a statistical beast and a pro bowler. I'm convinced that Shaun Alexander was never anything better than average. In Alexander's record breaking year, he ran for over half of his touchdowns without ever getting touched. That's the offensive line. Walter Jones was more important to that team than Alexander ever was. To say that Marshawn is between the 13th and 17th best running backs is just so utterly laughable. How could you possibly know that if you don't watch every running back and the holes that are created for him? What if the Bills pick up a beastly FB and suddenly Marshawn is running for 4.7 yards per carry. Did Marshawn suddenly become a better running back? Is he in the "top 5" if that happens?
For some reason (I think fantasy football has something to do with it), we love to rank players. In my opinion, running back is the least rank-able. I know that Marshawn is a strong running back, he's an intense running back and he's one of the few guys on the field that actually gives a damn on every single play. That's good enough for me.