One thing that I think is kinda interesting about the responses is that everyone is dividing natural ability and instruction in half, then placing "heart" as a kind of mystical plus. I believe that the ability to learn is just as much a natural ability as speed, power, etc.
And just as you can do drills to improve your speed, you can also work to improve your perceptions. I think a great example of this is Jason Bay's SBs. He's not that fast, but he was something like 23-23 stealing last year. He got caught, I believe, a few times the year before. He didn't get any faster and I don't think he improved his technique, but his knowledge improved. And for Bay, I think his greatest natural physical attribute might be his head (yeah, I know his head can't catch balls or run, but you get the point...)