Saturday, April 6, 2013

Whither Adam Dunn

I don't mean to be picking on Adam Dunn as much as I appear to, but when the wealth of data available is out there, it's hard not to see what it can tell us. As I did with Carlos Marmol, I'll use FanGraphs Pitchf/x data. This first chart shows various tendencies of Dunn's over his career:

The FanGraphs Pitchf/x Primer:
O-Swing%--the percent of pitches in which the hitter swings that are outside the strike zone
Z-Swing%--the percent of pitches swung at that are in the strike zone
Swing%--percent of pitches swung at
O-Contact%--percent of pitches the hitter makes contact with that are outside the strike zone
Z-Contact%--percent of pitches the hitter makes contact with that are in the strike zone
Contact%--percent of pitches the hitter makes contact with
Zone%--percent of pitches seen that are in the strike zone
F-Strike%--percent of first pitches that are strikes

There are two items that strike me, both of which I"ll graph, the first being the O-Swing%:

There is a marked trend in the number of pitches outside the strike zone that Dunn is swinging it. Along with that is the O-Contact%:

If you look at the rest of Dunn's data, you'll see that little has changed over the years--pitchers aren't really pitching him all that differently, but number of pitches that Dunn is making contact with outside the strike zone is increasing at a very high rate. Typically, when a hitter makes contact with a pitch like this, nothing good happens (check out this video for an exception--it's Manny Ramirez hitting a home run against the Cubs in the 2008 NLDS in which he appears to be using a 9-iron). In the best case, they're harmlessly fouled off, in the worst case, they're put into play as weak ground balls or other things that don't turn into a hit. This chart shows Dunn's batting average on balls in play in his career:

When you swing and make contact with balls outside the strike zone, precipitous drops in BABIP like this will occur. The major league average has held remarkably steady at around .300, so a two-year trend of a BABIP around .240 is cause for alarm. It's far too early to make predictions for this year, but it's not difficult to see a potential source  of Dunn's woes over the past two years.

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