Although Carl Pavano had nearly identical FIPs in 2009 and 2010 (4.00 versus 4.02), he achieved them in quite different ways. Pavano, who re-signed with the Twins yesterday, did a great job of limiting walks in both years. But in 2009 he combined that command with average-ish strikeout and ground-ball rates. In 2010, however, had just 4.8 Ks per nine (two per nine fewer than in 2009 and sixth lowest in baseball), but induced grounders on over 50% of balls in play.
Usually such a change in strikeout and ground-ball numbers is the result of a drastic change in pitch usage, see Joel Pineiro‘s 2009. But it looks to me like Pavano’s pitch usage has not changed that much from 2009 to 2010:
Instead the change comes from each of his pitches getting different results in 2010. Almost across the board his pitches have higher GB% and lower whiff (swinging-strike) rates. The only exception is his four-seam fastball had slightly higher whiffs in 2010. Swinging strikes and ground balls generally trade off, but it is interesting to see to play out so clearly for one player from year to year.
The difference is the most striking with Pavano’s slider which went from 37.5% GBs in 2009 to 59.2% in 2010, accompanied by a decrease in whiff rate (per pitch) from 12% to 10%. It looks to me that this was caused by location in the strike zone. Here is a plot showing the density of his slider to right-handed batters in 2009 and 2010, from the catcher’s perspective (so negative x values are inside and positive away).
You can see that he is getting his slider low and away much more in 2010. This is where a pitcher wants his slider to end up, and a location that will induce lots of weak contact on the ground.
Looking towards 2011, if Pavano can keep limiting walks and getting grounders he will be a valuable asset to the Twins even if he strikes out just a batter every two innings. But the margin for error for low-strikeout pitchers is small, and a little bump in walks or fly balls could be big trouble.
Hat tip to Millsy for the idea of using smoothScatter in R to make these types of pitch-density graphs.