Pretty negative on his hitting ability:
Billy Hamilton Scouting Report
by Adam Foster
April 18, 2011
You can only tell so much about a ball player from watching one round of batting practice. So I'll tell you more.
Billy Hamilton is a slick-fielding shortstop and a plus runner. A rhythm hitter with easy bat speed, he has plenty of swagger.
He's very thin with little room for physical projection. The switch hitter has poor pitch recognition and poor balance at the plate, a combination that will leave him at the mercy of advanced pitching. His swing is upper-body-driven and he's not a patient hitter.
Hamilton plays the game like it comes naturally to him, and he could be an above-average defensive shortstop. He ranges easily, has good hands, a strong arm, and is a fluid defender. But his odds of ever hitting in the bigs are slim.
He lacks the natural ability to square up on a baseball. And he doesn't have the frame or barrel awareness to hit for any kind of power.
I've talked to plenty of baseball people who are high on Hamilton's upside. Just be warned that he's going to be a big project at the plate, won't blaze through the minors and offers very limited offensive upside.