I think this will answer the OP's question, rather than drive the train on thought completely off the tracks:
Ezekiel Elliot does not have a "wow" trait. In other words:
His ability to break tackles is very good, but not great.
His acceleration is very good, but not great.
His top end speed is very good, but not great.
His ability to make defenders miss is good, but not great.
His vision, in my opinion, is exceptional. So is his pass blocking, and his receiving ability.
But these aren't things that show up on tape.
When I first looked at him, I wasn't overwhelmed, because of what I listed above. But you know what he does? He does EVERYTHING really well.
I parsed my thoughts on him a few months ago, about how I thought he did everything very well, but nothing extraordinarily well, and another poster said, "You just described Emmitt Smith."
I think he's spot on. And I think that's what lets him drop to 13.