I pointed out that Porcello does not actually under perform his expected K9 by much, although his low projection itself is a concern.
However Wang and Edwin Jackson project to be at least league-average K9 pitchers, but have both consistently struck out many fewer batters than expected. From the table linked below, let's pull a list of starting pitchers (100IP+) who projected to have at least 6K/9, but significantly underperformed in reality (in order of under-performance):
- Chien-Ming Wang 2006
- Danny Graves 2003
- Carlos Silva 2005
- David Wells 2003 (actually not a bad season: 15-7 4.18 ERA for the Bombers, 4.6 WARP)
- Fausto Carmona 2008
- Jason Johnson 2005
- Jorge Sosa 2005
- Kyle Lohse 2005
- Bronson Arroyo 2005 (last season in Boston, 1.9 WARP)
- Edwin Jackson 2008
- John Lieber 2004
- Jorge Sosa 2003
- Chien-Ming Wang 2005
- Sidney Ponson 2004
- Mike Hampton 2002 (his horrible last season for the Rockies)
- Zack Duke 2007
- Jeremy Guthrie 2009
- Horacio Ramirez 2005
- Hiroki Kudora 2008
Still, being listed here as one of the top unexpectedly low K9 seasons in the last 10 years is not really a positive projection for a a pitcher's future.
I think the Yankees are doing the right thing by not committing to Wang, but this comment might have been more meaningful if it had been made two years ago. At this point, he is "injury prone," rather than a surprisingly effective low-strikeout pitcher. The predictive power of pitcher injuries is another topic that I have been looking into. Maybe I'll have something on that front soon.
Edwin Jackson is another matter. He is just coming off a career season. After a disappointing development prior to 2009, he put a solid 3.9 WARP in 2009, despite some late-season decline. However, he still continues to strike out many fewer batters than one would expect given his stuff (ie pitches and bio information). In 2009, he posted 6.77 K/9, while my system would expect him to put up 8.49 K/9. That 1.72 K/9 under performance is still in the bottom 10% of pitcher seasons between 2002-2009.
The D-backs recently traded for Jackson, giving up Max Scherzer as part of the deal. Scherzer projected for 7.0K/9 in his first full major league season, but in fact struck out 9.2 per 9 innings.
I'm not saying that my work here proves anything, but I'm not sure why the Diamondbacks are giving up a young pitcher with one solid season (and a solid K/9 over achievement) for a young pitcher with one slightly better season, and several year's worth of consistently recording fewer strikeouts than expected. Hopefully, they are not expecting Edwin Jackson to start striking out a lot more hitters next year, since he has a multiyear history of under performing those expectations. On the other hand, there is a possibility that Scherzer can keep his strikeout totals above expectation (and well above the league average).
Of course strikeouts are not everything, but they are pretty important for predicting pitcher longevity and long-term success. Bill James wrote a long time ago about how almost no pitchers have long careers without early-career strikeout totals that are above league average. I have never seen anyone try to prove the contrary. I have not done any multi-year value studies of pitchers, so perhaps when I do, there will be something else to say.
In the mean time, I am close to publishing some results for my overall value and predictions. Once I have a system that I'm comfortable with, and one which does well in historic tests with PECOTA & CHONE, I will write about it. Also, I should probably publish 2010 projections at some point. If I wait until I make all the improvements that I can, I will never publish anything!