What's the Matter with Wuertz? Is He a Bum?

Last year Michael Wuertz had a dominating season, putting up an ERA of 2.63 and striking out 102 batters in just 78.2 innings -- a rate of 11.67 K/9, good for fifth among all pitchers with at least 40 innings pitched.  The A's rewarded Wuertz with a 2 year $5.25 million contract in the offseason and expected him to be a key part of the bullpen this year. 

Unfortunately, his season got off on the wrong foot and he missed almost all of Spring Training and all of April with a shoulder injury.  Things haven't been much better upon his return as he's allowed 8 runs in 11.1 innings.  I know its early, but its not just his ERA that is ugly, there are some disturbing trends in the underlying data.

One of Wuertz' bugaboos going into the 2009 season was his control.  In every year between 2004 and 2008 he walked at least 4 per 9, except in 2006 when he lowered his walk rate to 3.54.  Not coincidentally, he posted middling ERAs between 3.50 and 4.00 in every year except for '06, when he posted a 2.66 ERA.  So far in 2010 he's walked 7 batters in his 11.1 innings (one intentionally), which translates to a BB/9 of 5.56.  It's his command of his fastball that's really let him down so far.  Last year he threw his heater for a strike 60% of the time and this year his fastball has found the zone only 48% of the time.

His fastball has also lost a bit of zip, averaging only 89.3 MPH this season compared to 91.0 MPH in '09.  As a result, the whiff rate on his fastball has dropped from 4.4% to just under 3%.  His slider is also less effective, though its unclear whether this is because of his weaker fastball or a change in his slider.  In 2009, Wuertz threw his slider with an average velocity of 85.8 MPH, with 3.58 inches of vertical break and -0.02 inches of horizontal break.  So far in 2010, his slider's only averaged 83.8 MPH.  The vertical break of the pitch has been close to its '09 level at 3.42 inches, but its horizontal break has averaged 0.60 inches.  Whatever the cause, his slider has gone from being worth 2.63 runs above average per 100 pitches last season, to being worth 2.31 runs below average per 100 pitches this season.

Obviously an 11 inning sample is too early to make any hard conclusions about Wuertz so far, but his control and velocity are down, which has led to not-so promising results.  Based strictly on the numbers, it seems that Wuertz may still not be 100% healthy, though there haven been no reports that his arm is still bothering him.  Perhaps he's still rounding into form and missing Spring Training really hurt him.  Either way, it's pretty clear that Michael Wuertz right now is not the same pitcher he was in 2009.  We'll have to keep an eye on his control and his velocity to see if he becomes that guy again.