The 28 year-old was a 3rd round pick in 2004 and was one of the big chips the Phillies traded last year to get Oswalt. He is 20-9 in his major league career, with a 3.42 ERA (but a 4.43 FIP), and 1.32 WHIP. His career BAPIP is .268, thus the reason why the low ERA compared to his FIP.
He's a fly-ball pitcher, who throws from a high 3/4s arm angle and creates deception. His fastball sits between 88-90, with an 84 mph slider, 75 mph curve, and 79 mph change-up. He has increased his curve ball use this year to 14% (from 7%). He doesn't have swing and miss stuff (7.6% career, 5.8% this year), which leads to his below average K/9 rate (6.7 career), and just a mediocre walk rate (3.8 BB/9 career).
This year he's 2-4 in 7 starts (40 2/3 innings), with a 5.75 ERA, 1.52 WHIP due to a 4.2 BB/9 (was over 5 when he faced the Mets April 21). His K/9 is still below average (6.2 K/9), his ground ball rate is a career low 26%, which isn't a recipe for success in the band box known as Minute Maid Park. His BAPIP has regressed to the mean (.306), and he's having trouble stranding runners, thus the elevated ERA.
He faced the Mets on April 21st, and took the loss, only lasting 4 2/3 innings, let up 6 runs, 2 home runs (Wright and Nickeas). He's started 5 games against the Mets (2 relief appearances), and is 1-2 with a 5.17 ERA and 1.47 WHIP. He did not face the Mets in 2010.
He's a back-end of the rotation pitcher, who is not perfect for the Astros ball-park, unless he switches to become more of a ground-ball pitcher.