So let's take a look at his stats.
Starlin Castro Statistics and History - Baseball-Reference.com
You know he can hit for contact pretty well. The power isn't there yet, but he does get his share of doubles and triples. He's also 20-steals fast.
He's also walking 2% of the time he has a plate appearance. TWO. PERCENT. They have no fear of throwing him strikes because they know that if he puts the ball in play he's getting himself out about 70% of the time and they'll risk it. He doesn't have the power to consistently slam the ball over the wall. There's no incentive to pitch around him, and they also know he's aggressive which is why he looks so terrible on swinging strikes. His saving grace is his batting average and that fluctuates wildly. Right now he's getting on base at a rate less than Tony Campana and Darwin Barney, and that's pretty fucking sad. On the plus side he's slugging better than the other two (I won't even get into wOBA because I know some people will shit themselves) but even with his decent batting average he's still a below average offensive player.
That is okay, because SS is the most valuable position on the field so you can accept slightly below average there, but he also seems to have improved on defense. Motions look more fluid. Throws with more confidence. Still has tons of range and athleticism. I don't trust defensive metrics any further than I can throw a baseball so I don't think the dWAR tells you anything, but my lying eyes tell me he's got the drive to become at least a solid defender.
