The 6'3" Kartsens was drafted in the 19th round by the Yankees out of Texas Tech in 2003, and made his major league debut in 2006. In the small sample size of 15 games for the Yankees (9 starts), his ERA was 5.65 and a 1.51 WHIP. He's been a better pitcher for the Pirates, but nothing to really right home about (8-21 record, with a 4.8 ERA and 1.41 WHIP). Against the Mets, he's started twice (2008 and 2009) and faced them once in relief (2009), and he has a 5.27 ERA and a 1.46 WHIP.
Karstens barely breaks a pane of glass with his fastball, which sits at 89 mph, but he only throws it 55% of the time, and mixes in a slider (80 mph), change-up (80 mph) and curveball (72 mph) equally. His curveball has been his only plus pitch this year. How does he succeed? Well, he pounds the strike zone, throwing 65+% of his pitches for strikes, which is in the top 20 in baseball. He doesn't get many swing and misses (7.6%), and his K/9 is too low (5.1), but he doesn't walk many, 2.1 W/9. He uses his slider and curveball equally with two strikes. Also look for a ton of 1st pitch fastballs, as he throws it 66% of the time.
This year Karstens is 2-9 in 17 starts (23 appearances), and he has a 4.57 ERA and 1.39 WHIP. He has gone at least 5 innings in 14 straight starts, but has only gone 7 innings once. He has lost his last seven decisions. His last start versus Houston he went 5 2/3 innings, and let up 5 runs on 7 hits and 1 HBP.
He's a #5 starter/middling long reliever in his future. And his future is now.