Harris has a better arm than Robles but as a rookie already has more common sense to just throw that to second. Do the Braves draft smarter players or just develop them better?
Maybe all of that, plus less arrogant. I remember seeing Robles with the P-Nats and my biggest concern being that he had far, far too much smug swagger for a dude in A ball. Pimping homers is one thing; strutting around after throwing a ball in on a single to center is another. It presents a barrier to actually learning. He's just a stupid, arrogant player who doesn't seem to let reality dent his self-appraisal.
But I don't think the crap-for-brains that is Victor Robles is more than a one-off. Most of it is development, some of it is drafting/signing. It's a pretty jarring contrast with Harris, though, who has always been a smart player from when I first saw him in high A.