I saw video of him running through drills at the regional combine and boy did he look stiff. He does seem to have good athleticism for a guy his size, but his movements just didn't seem fluid. In other words, while he seemed to have a lot of athletic ability, he didn't really move like an athlete, if that makes any sense. I'm sure he will improve with experience, but at first blush the guy didn't seem like a natural football player at all.
You can learn a lot, but in many ways, either you are a football player or you're not.