"Ryan's been a really good addition to us," Kelly said. "[He's a] big, physical running back. I don't think you really know actually how big he is until you actually pull up next to him . . . He's explosive. When he sees a hole, he can change gears and accelerate through it. We're using him a little bit on kickoff return, I think because of taking advantage of that speed. There's not a lot of guys that have that speed to go along with that size.