I don’t think we can’t say with any absolute certainty

It's too early in the morning for this....

It's too early in the morning for this....

Hey man, it was even earlier when I wrote that. Fixed.

The sample size is very small, but there are a lot of possibilities that are simpler explanations than "Wang refutes dips theory." Off the top of my head:

1. Small sample size. Are the results the same for his previous seasons?

2. Problems with using ZR as the defensive measure (although the need for splits probably makes it your only choice).

3. The long grass in the Yankee IF helping him out by slowing down his ground balls and making them easier to field. If you further slice the data, how does it look in comparison to Wang's H/R splits (which IIRC are already pretty pronounced).

4. Sinkerballers exhibit a tendency similar (though to a lesser extent) to knuckleballers regarding the kind of contact they allow (wasn't there already a study done in relation to this?); does Wang's increased GB rates account for fewer hits and that is being reflected in his IF ZR scores?

1. Small sample size. Are the results the same for his previous seasons?

SSS is a big concern. Unfortunately I don't have daily ZR splits prior to 2007.

2. Problems with using ZR as the defensive measure (although the need for splits probably makes it your only choice).

Yeah, ZR is far from perfect but it's pretty good IMO.

3. The long grass in the Yankee IF helping him out by slowing down his ground balls and making them easier to field.

If that was the case then we should see the same effect for all Yankee pitchers, shouldn't we? I like the H/R split idea, I'll have to mess around with that.

4. Sinkerballers exhibit a tendency similar (though to a lesser extent) to knuckleballers regarding the kind of contact they allow (wasn't there already a study done in relation to this?);

Yes, that does sound familiar, although ground balls are more likely to be hits than fly balls. One of the posters wondered about a similar study for Brandon Webb, which I'll probably look at. Fausto Carmona would be another good one.

This is not meant to be a definitive study by any means, I just thought it was an interesting idea and wanted to see what the numbers said.

Isn't this basically the With or Without You analysis from this year's Hardball Times Annual? I'd like to know how WOWY sees Wang's fielders.

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.

This is almost certainly the case.

Various people have noted this (pitching-as-part-of-defense) a likely 'next step' in the DIPS-style analysis. I think this is an interesting way to think about that issue, and as noted it's one that we've seen other things on over time. I'm curious to see the next step forward on it.

If that was the case then we should see the same effect for all Yankee pitchers, shouldn't we?

Do any of the other Yankee pitchers have Wang's GB rates? I thought it would be a matter of scale; with this being a noticeable abberation in Wang's fielder's numbers because he gets so many more GBs than the rest of the staff. With the rest of them being so much closer to neutral the distortion might be covered by the statistical noise.

although ground balls are more likely to be hits than fly balls.

I was thinking that his increased GBs subtracted from the amount of line drives that he gives up (although I'm not sure where I'm coming up with that assumption). Wasn't there also a study that showed that hitters tendencies can affect this? (I remember a David Ortiz vs Wang comparison somewhere...)

If that was the case then we should see the same effect for all Yankee pitchers, shouldn't we? I like the H/R split idea, I'll have to mess around with that.

Not necessarily. The Yankees could leave the grass longer when Wang pitches, and cut it short for the other guys, thinking they'll be helped more by letting Jeter get a few more groundball hits.

Overall, my retrosheet defensive stats show that Yankees have a tough infield for fielders, groundballs are more likely to become hits there. The effect isn't huge, adjusting for it adds about 3 runs a year to Jeter's rating, but the effect does not have to be uniform for all pitchers.

At the same time, opposing teams would want to cut their grass short with Wang on the mound. I wonder if groundball pitchers show larger home/road splits than normal? There really isn't anything you can do to mess with or help a flyball pitcher like that.

There really isn't anything you can do to mess with or help a flyball pitcher like that.

indoor stadium + humidor!

I did a quick query on the fraction of ground balls that result in outs for Wang and for all other Yankee pitchers from 2005-2007. Here are the results:


Wang does give up more fieldable ground balls.

The home/away splits for Wang are pretty interesting, too:

Looks like the grounds crew are earning their keep.

Wasn't there a study in a THT annual that found park factors for grounders a couple years ago? IIRC, the Indians and Dodgers were at the top of the list of groundball parks.

Not necessarily. The Yankees could leave the grass longer when Wang pitches, and cut it short for the other guys, thinking they'll be helped more by letting Jeter get a few more groundball hits.


I think you are ascribing more value to (most often) a single day's growth of grass than is really warranted. On occasion---e.g. where he's pitching the first game back from a road trip---it might be enough to matter but most starts I just don't think the grasscutting is going to make a huge difference.

I think watering down the grass can make a big difference, though.

The home/away splits for Wang are pretty interesting, too:

+------+-----+------+-----------------+
| H/A | gb | outs | gb_out_fraction |
+------+-----+------+-----------------+
| Home | 641 | 503 | 0.7847 |
| Away | 493 | 364 | 0.7383 |
+------+-----+------+-----------------+


Looks like the grounds crew are earning their keep.

I wonder what those splits would look like with Minnesota, Tampa and Toronto excluded.

Ground ball pitchers DO allow easier to field ground balls and fly ball pitchers allow easier to field fly balls. I make adjustments in UZR for the GB/FB ratios of the pitchers behind each fielder. So the first thing to do is to compare Wang's GB out rate to that of other extreme GB pitchers. I think you will find that it is not all that different.

MGL:
Slightly off topic, but: Have you ever turned this around to see if UZR captures the full impact of hitters? That is, suppose you take a certain group of GBs defined by the UZR parameters -- zones x, y, or z; LHH; avg GB/FB pitcher, etc. -- and find the average out expectation for these GBs is 75%. If we then divided these GBs into groups defined by the BABIP of the hitters (or even better, the hitters' BABIP on GBs), would we find that the out% on those hit by the .320+ BABIP hitters is the same as those hit by the under-.280 hitters? Or to the extent that isn't true, could you then use hitter-BABIP as a parameter to create more accurate out expectations?

would we find that the out% on those hit by the .320+ BABIP hitters is the same as those hit by the under-.280 hitters?

Isn't that circular reasoning (selective sampling)? Of course, if we did look at something like that, we would look at high and low BABIP batters from a different sample (like career or last few years prior to the UZR sample). In any case, I have never looked at this.

It is actually an interesting issue, as we would expect that guys with more power to hit harder ground balls. Of course, to some extent, that is captured in the speed designation (soft, medium, or hard) of the ground ball. Then again, a hard hit ground ball by a power hitter is probably hit harder (and thus has a lower out%) than a ground ball by a non-power hitter. That is a good suggestion though - to adjust for the power of the batter, using out-of-sample data for the power designation. That probably applies to fly balls or at least to line drives. Actually, the harder hit a fly ball is, the easier it is to catch (higher out %) I think. Interesting idea.

Actually, the harder hit a fly ball is, the easier it is to catch (higher out %) I think.

The "hardness" factor for a fly ball is a measure of how "far" it is hit (at least in the BIS data, and I'm pretty sure it's true in the STATS data as well). Fly balls that are hit to the deepest part of the OF (assuming they stay in the park) tend to hang in the air longer, giving the fielders more time to react and catch up with them.

-- MWE

I wonder what those splits would look like with Minnesota, Tampa and Toronto excluded.

Here are the numbers with turf parks removed:



The difference gets smaller and, in fact, is not statistically significant anymore.

MGL: You may be right that using out-of-sample BABIP for the hitters is better. But I'm not sure it's necessary. If UZR were providing a "perfect" measure of fielding difficulty, shouldn't the balls hit by a .320 BABIP hitter have a .68 out probability? But my guess is that a good hitter out-performs his own UZR estimate.

I was thinking that this would be more valuable on GBs, as hitters vary quite a bit on their GB hit rate. Is there a lot of variance on non-HR FBs and LDs as well?

For multi-year UZR scores this probably won't change much, as hitters faced by fielders should even out. But it might improve accuracy (and narrow variance) in single-season estimates.