by Daniel Gettinger

Jake Peavy has started five games.  He has pitched 31.1 innings, and has a 5.74 ERA.  Something must be wrong, right?  Well, not exactly.  While I will not try to argue Peavy has been exceptional in 2009, his underlying stats do not demonstrate any conclusive reasons to be concerned.  Pitch FX data does show a possible loss in fastball velocity, and while this is something to monitor going forward, I again am cautious about drawing any conclusions about Peavy’s future effectiveness.

While Peavy has a 5.74 ERA, his FIP, which attempts to weed out some of the luck inherent in ERA, stands at a much more acceptable 4.05.  This difference is mostly attributed to a ridiculously high 0.340 BABIP.  For comparison’s sake, in 2008, Peavy had a 3.60 FIP.  In fact, Peavy is actually striking out more batters per nine innings than he did in 2008 (9.19 v. 8.60 K/9).  What has hurt Peavy is an uptick in walks and home runs allowed.  In 2009 Peavy has allowed 3.73 BB/9 compared to a career rate of 2.92.  His HR/9 currently sits at 1.15 compared to 0.92 for his career (note: the career rate is adversely affected by a 2003 season in which he gave up 33 HR, a number he has never come close to approaching again).

Normally I would not be too concerned about these numbers.  Peavy has not pitched enough innings in 2009 to make any definitive statements regarding a loss of control or a decreased ability to prevent the long ball using the statistics alone.  What concerns me though is the possibility that the increased walks and home runs allowed are a result of decreased fastball velocity.

In 2007, Peavy’s best season, he threw his fastball 62.4% of the time at an average speed of 93.9 MPH.  In 2008, he threw the fastball 58% of the time at an average speed of 92.6 MPH.  In 2009, he has thrown the fastball 52.2% of the time at an average speed of 91.7 MPH.  The horizontal and vertical movement on the fastball have remained fairly constant.  Only the speed of the pitch has changed.

Instead of throwing his four-seamer, Peavy is relying much more on a curve and cutter than he has in the past.  There are two primary explanations.  The first, and the more disheartening of the two, is that Peavy no longer has the stuff to overpower batters with his fastball.  Instead he is substituting towards the curve and cutter, pitches he does not control as well.  Decreased pitch speed could explain the increase in home runs allowed, while throwing more curves might be contributing to the increase in walks.

I prefer to take a more optimistic view.  I do not believe there is ample evidence to conclude Peavy’s fastball is slower than in 2008.  It is very possible that as the weather warms, so will Peavy’s arm.  By June, Peavy may be back to throwing 92-93 MPH on average.  In addition, I believe Peavy is throwing the curve ball more often because he has improved the pitch, not because he believes his fastball is less effective.  Compared to 2008, Peavy’s curve ball in 2009 has had double the vertical movement.  Perhaps he is experimenting with the pitch because he knows eventually it will become a useful and effective part of his arsenal, protecting against a true loss in velocity down the road.

It may be true that Peavy no longer has the stuff to overpower batters with the fastball.  But, at this point, I feel such conclusions are premature.  In the past, Peavy has had 5-game stretches where he appears to have performed poorly.  And he will have such stretches in the future.  Most of the time, Peavy’s performance in these stretches has been a tad below-average, but also exacerbated by bad luck.  This five start stretch is no different.  Peavy has not pitched as well as we have seen in the past, but a 0.340 BABIP has more to do with his 5.74 ERA than his actual performance.