When J.A. Happ was dealt to the Houston Astros earlier this season as one of the centerpieces in the Roy Oswalt deal, it was leaked that there were those in the Astros organization who thought Happ was a Cliff Lee type pitcher. Lee has been a dominating force and one of the most productive pitchers in baseball for the past three seasons, so it seemed an odd comparison to make, given Happ's track record in terms of his peripherals–he whiffs opponents around an average rate and walks too many hitters to post a quality K/BB like Lee does. Despite this, Happ has pitched well since the deal, posting an ERA of 3.21 while winning five of his eight starts for the 'Stros.
It seems there are two camps when it comes to Happ–the one that thinks he's a high quality pitcher as evidenced by his ERAs, and the one that thinks he is a league average hurler who has been lucky in terms of ERA. He has certainly given the former some ammunition this season, with a 2.86 ERA across 63 innings, but it's that number at the back that's important to remember–it's just 63 innings, and his peripherals do not support this ERA. Happ is striking out 6.9 hitters per nine, right at the league average for starting pitchers, while giving out unintentional free passes to 4.7 per nine. His K/BB is 1.4, well below the league average of 2.2, as well as nowhere near the realm of being able to support that ERA.
With Houston, Happ has whiffed 7.4 per nine and walked 4.2 per nine, which gives him a K/BB of 1.8–it's better, but it's still below the league average. His .231 BABIP for the season has helped him immensely, and while his supporters will say he doesn't allow hitters to make good contact against him–hence his ability to out pitch his peripherals in terms of ERA–this is well beyond that territory and will regress. Happ's SIERA with Houston is 4.29, which is actually worse than the league and NL average. Happ has also posted above-average strand rates, thanks to his career line of .176/.278/.241 allowed with runners in scoring position. That's in just 199 at-bats though, so it's not a sample size we can trust just yet–it may be indicative of something in terms of Happ's ability, but it's tough to draw any kind of conclusion from it, especially when his career line with runners on in general isn't much different than his line with the bases empty.
Houston's defense has not been good this year either, coming in at #25 in Defensive Efficiency, but Happ has managed to avoid this by being a severe flyball pitcher–Carlos Lee isn't any help out there, but Michael Bourn and Hunter Pence can both field well. The fact he's induced pop ups on over 19 percent of his flyballs has also helped, but that's nearly double his career rate and we're talking about a very small 63 inning sample here.
There's a temptation to hold onto Happ because of some enticing figures in his stat sheet, but unless you have him for a low, low price or are in an NL-only league, he's not someone you want to use the slot on. Happ may be better than his peripherals suggest due to the contact he induces, but a full run or more better, as his ERA for the year and with Houston suggests, is the work of small sample smoke and mirrors more than those wielded by Happ.