Tuesday, January 1, 2008
The Wang Effect?If you're a baseball fan with at least some proclivity towards stats, you're probably familiar with Voros McCracken's DIPS theory. McCracken basically stated that a pitcher's ability to control what happens on balls in play is variable and volatile. Some overly extreme devotees to this theory take it to mean that a pitcher has zero control over a ball hit into play, but that's not really true. If it was, you wouldn't have groundball pitchers and fly ball pitchers. Also, selection bias would mean that anyone who reaches the majors may have a certain level of skill on balls in play that allowed them to get that far. I still think DIPS theory is useful in many ways, primarily because it taught me to look more closely at a pitcher's peripherals, but it's really just a fraction of any evaluating of pitching that I do.
One of the often-stated mantras about Chien-Ming Wang is that he generates easily fieldable ground balls, which means his success despite a low strikeout rate is not really that much of a fluke. It's possible this is true, at least in the regular season, but is there a way to quantify it?
I recorded zone rating daily throughout 2007 to see if I could use the day by day data to answer questions like this. Here's a look at what the numbers showed.
GS: Games started
Ch: Fieldable chances as defined by zone rating
INN: Defensive innings
ZR: Zone rating (PM/Ch) PM: Plays made Diff: Plays made compared to average This is how the Yankees did as a team in 2007. Overall they made 18 plays fewer than average.
Here's a look at how the team did in the games Wang started. This does include all innings in those games including those not pitched by Wang, but I have no way to separate those out.
Interesting, huh? In the games that Wang pitched, the team was 10 plays better than average.
Lastly, here's the team in games Wang did not start.
|Total - Wang||1059||918||2463||8192.9||2580||1019||67||354||.825||2031||-28|
A few things to bear in mind about this data before we make too much of it.
1) It's only one year. Unfortunately no one I know of tracked daily zone rating before this season so sample size is an issue.
2) Like I said, this includes innings pitched by relievers and not just Wang. That muddies the numbers up a little.
3) BIP (ball in play) distribution. Perhaps Wang's balls in play just happened to find their way to the better fielders on the team? We can check that too.
Columns prefaced with a w are the stats in the games started by Wang, columns prefaced by an nw are the non-Wang games. The ZR ratio is the difference between each player's zone rating in Wang games and non-Wang games. A percentage less than 100 means they were worse in Wang's starts and a percentage greater than 100 means they were better in Wang's starts. I'm not looking at runs saved here, but plays made above/below average. Rough rule of thumb is .8 runs per play although it varies a bit by position
Again, I don't know how meaningful this is due to the sample size and non-Wang innings in the 30 Wang games but I think it's pretty cool to look at. Robinson Cano, Derek Jeter, and Alex Rodriguez all had better zone ratings in Wang's starts than in the other games. The first base collective did worse. (wil Nieves at first? WTF?). What's interesting to me is that even the OF saw a boost in games started by Wang, with the exception of RF and Bobby Abreu.
I don't think we can say with any absolute certainty that Wang does allow more easily fieldable balls in play than the typical pitcher, but there's at least circumstantial evidence that he may. It'll be something worth following going forward. It may also make us want to think a little bit more about DIPS theory and about how we assess defense. Just like pitching is partly-related to defense, perhaps defense is partly-related to pitching.
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