Per Pirates Prospects. Sampson has certainly earned the promotion. He has a 2.55 ERA, 1.05 WHIP and .229 opponents' average. He's not striking out a ton of hitters, with 99 in 148 innings, but he's been increasingly efficient with his pitch counts and he's steadily gotten better overall. In July and August he's gone 5-0, 1.96 with a WHIP of 0.93.
UPDATE by Charlie: Kyle Stark said a couple weeks ago that Sampson would likely be promoted to Indianapolis at some point. That was a few days after Sampson flirted with a no-hitter against Bowie. His strikeout rate is still a bit low, so it will be interesting to see how he does at Triple-A, but guys like Vance Worley, Brandon Cumpton and Jeff Locke have shown at the big-league level this year that you don't necessarily have to strike out a million batters if you don't walk anyone. Sampson's control should serve him well.