The only Kevin Barry I knew of was the martyr in the Irish war of independence back in the 1920s, so I looked this one up in the Baseball Prospectus:
"His numbers at Richmond look decent enough until you consider his age [28]. Barry's an organizational arm whose greatest contribution to the Braves in 2006 was a pulse. He gave up a ton of fly balls, opponents slugged an unsurprising .442 against him, and he responded by nibbling and walking people. He's unlikely to see much time in Atlanta in the future, lest some apocalyptic pitching scenarios arise." (emphasis mine)
He apparently pitched 25 innings in Atlanta last year, but honestly I don't remember him. It must have been in mop-up duty late in the year when the Braves were out of it and college football had started up. His minor-league stats haven't been bad, but as it says, he's 28, so he's not really a prospect. My guess is that he's been brought up for long relief while somebody else (probably Villarreal) goes into the fifth spot in the rotation.