Groundball % in 2006

[sfgiants88]

I have read on this forum that decreasing groundball % actually decreases the expected ERA in the editor. I am curious how exactly this works. Lower groundball % should lead to more homeruns and thus a higher expected ERA right?

Also, with regards to homeruns allowed, how big of a factor is groundball % compared to movement? What kind of interplay is there between these two ratings?

Thanks

[Elendil]

Originally Posted by sfgiants88

I have read on this forum that decreasing groundball % actually decreases the expected ERA in the editor. I am curious how exactly this works. Lower groundball % should lead to more homeruns and thus a higher expected ERA right?

Also, with regards to homeruns allowed, how big of a factor is groundball % compared to movement? What kind of interplay is there between these two ratings?

Thanks

HR allowed are apparently affected only by the movement rating, not GB %, in OOTPBM2006. That's the reason more groundballs are bad: higher BABIP, but no benefit in terms of fewer homeruns.

[scotto313]

I am trying to understand why higher GB% leads to higher BABIP. If I have all top range and fielding% infielders shouldn't a high GB ratio lead to a lower BABIP?

[Elendil]

Originally Posted by scotto313

I am trying to understand why higher GB% leads to higher BABIP. If I have all top range and fielding% infielders shouldn't a high GB ratio lead to a lower BABIP?

Well, yes, you need to attach a "ceteris paribus" rider to my statement. If your outfielders suck and your infielders are awesome, then your GB pitchers may actually have a lower BABIP than your FB pitchers.

The logic for the statistical finding that GB pitchers have higher BABIP is that more groundballs scoot through for hits than flyballs drop for hits.

[kq76]

Regarding groundball pitchers being better than flyball pitchers:

Getting back to the possibility of certain classes of pitchers having unique hit preventing abilities, it should be clear that fly ball pitchers, on the average, will have a different $H than will ground ball pitchers, since a fly ball has a higher out percentage than a ground ball. In fact, extreme ground ball pitchers have a BABIP of .297 (1992-2003), whereas extreme fly ball pitchers have a BABIP of .281 (extreme = top and bottom 10% in G/F ratio for pitchers with at least 100 BIP in a season). Of course, the run value of a FB hit is greater than that of a GB hit, such that the actual run value of all pitchers� BABIP is almost exactly the same, regardless of their G/F ratios.

-Mitchel Lichtman (MGL) http://www.baseballthinkfactory.org/..._2004-02-29_0/

Of course, that source doesn't show the data behind that, but I'm pretty sure that part about FBs resulting in more runs is considered common knowledge and MGL is a well-respected sabermetrician.

In another thread I questioned whether flyballs really resulted in more outs, but if MGL says they do then I'll take his word for it.

And to continue my attack on ERA:

And the relationship is a strong one. The correlation between the percentage of a pitchers runs that were unearned and his ground ball rate is .33, which means that ground ball pitchers are expected to allow more unearned runs than fly ball pitchers. Of all ground balls, 2.23% end up as an error, which accounts for 85% of all errors overall. Since ground ball pitchers are so susceptible to errors, they're bound to see a lot more unearned runs. It's not bad defense that's resulting in those runs being unearned, but rather the pitcher's ground ball tendencies.

What this means is that we might actually overrate some ground ball pitchers on the basis of their ERAs. Take Derek Lowe, for example. His ERA last year was 3.61, a respectable 13% better than league average. It's easy to be deceived into thinking he had a good year last season, if you don't take the unearned runs into consideration as well. However, if you do, Low was actually 7% worse than league average. When it comes to ground ball pitchers, ERAs can be deceiving.

-David Gasko http://www.hardballtimes.com/main/ar...-the-grounder/

So while a high GB% should usually be a good thing, I'll admit it shouldn't be as good as you might think especially if you look at RA instead of ERA.

Finally, but probably most importantly, besides their GB% pitchers probably don't have a whole lot of control over their HR rate:

Nate Silver of Baseball Prospectus has argued (subscription required) that a pitcher's groundball rate may in fact be a better predictor of home run rate in future seasons. A pitcher's groundball rate does not fluctuate too much from year to year, and pitchers with low groundball rates give up home runs much less frequently than fly ball pitchers. In fact, the reason that home runs correlate fairly well from year to year may be partially that they're a proxy for a pitcher's groundball/flyball rate.

-Tom Meagher http://www.hardballtimes.com/main/ar...the-long-ball/

Other sources:

http://www.hardballtimes.com/main/ar...the-long-ball/
http://www.baseballprospectus.com/ar...articleid=2885

So, what I'd like to see is not necessarily get rid of the movement rating, but have it strongly depend on a pitcher's GB% and so, like in real life, a high GB% should usually result in a better pitcher, not a worse one like with OOTP2006.

[Seviien]

Do we know if the generation of GF is linked to movement rating? That would make sense...

[cabot41]

In regards to the Gasko piece, I think you can really take those stats either way. In that kind of analysis it is necessary to point out that we have a (generally speaking) better and more consistent way of capturing infield errors than outfield errors. A groundball pitcher is going to generate more errors simply because offcial scorers are reluctant to give OF errors unless the unwritten "ball touches the glove" rule.

In any event, for the purposes for this sim, it seems to me that GB pitchers shouldn't neccessarily be better or worse than FB pitchers, its just that the two types should have to rely on different things when contact is made. A FB pitcher playing in front of a great outfield defense and in a spacious "Petco-like" ballpark should do better than his underlying stuff/mov/con ratings would suggest, and a GB pitcher with a gold glove double play tandom should do better than his FB counterpart playing in a bandbox. I haven't paid enough attention to get a feeling as to whether the sim is in fact doing this or not, but I the other important point to make is that these differences should really only be noticeable in the most extreme cases of each. A 60 GB% shouldn't read all that differently than a 50% imho.

[mrbill]

Well, if there's any studies that show that homerun rate is completely correlated to movement AND that movement is not correlated to GB%, then I'll be disappointed greatly in this version.

[RonCo]

Markus has been working on GB% vs. HR production in v2006 ... I have every expectation that it will settle out pretty well with respect to the data that's been linked here.

[Linenoise]

Originally Posted by cabot41

In any event, for the purposes for this sim, it seems to me that GB pitchers shouldn't neccessarily be better or worse than FB pitchers, its just that the two types should have to rely on different things when contact is made. A FB pitcher playing in front of a great outfield defense and in a spacious "Petco-like" ballpark should do better than his underlying stuff/mov/con ratings would suggest, and a GB pitcher with a gold glove double play tandom should do better than his FB counterpart playing in a bandbox. I haven't paid enough attention to get a feeling as to whether the sim is in fact doing this or not, but I the other important point to make is that these differences should really only be noticeable in the most extreme cases of each. A 60 GB% shouldn't read all that differently than a 50% imho.

As a lifelong Ranger fan I can attest to this assertation. The Ballpark is second only to Coors Field in the number of rockets fired into space every year. The Rangers have always had hell getting decent pitchers to play here because unless you are a GB pitcher this field will add atleast one full point to your ERA.

[Linenoise]

Of course the otherside of the argument makes total sense to me aswell. One of the things that makes baseball so great is all of it's talking points. Afterall it is the King of talking sports sport. I suppose it is because it is so heavily ladden with statistics and if one thing is certain in life it is this: Statistics are never certain!

[sfgiants88]

Originally Posted by RonCo

Markus has been working on GB% vs. HR production in v2006 ... I have every expectation that it will settle out pretty well with respect to the data that's been linked here.

Any update on this? Has it been addressed in 2006? If not, what about 2007?

[LASpirit]

In most of the statistical examples I have seen, GB%, LD% and FB% have HRs removed from their calculation and treated as a separate entity.

[RonCo]

Originally Posted by sfgiants88

Any update on this? Has it been addressed in 2006? If not, what about 2007?

Both movement and GB% influence HR in OOTP2006.

[RonCo]

The testing data I took on this was clear, repeatable, and within shouting range of MLB GB% vs. HR rate data published on FanGraphs.

http://www.fangraphs.com/blogs/index...search/page/2/

[sfgiants88]

Very good news. Thank you.

[jm47048]

Yes, if you're not chaning the HR's allowed number, and only the ground ball number, you are taking away that ground ball that squeaks through the infield. SO it would just be converted to a fly out.

[RonCo]

Originally Posted by jm47048

Yes, if you're not chaning the HR's allowed number, and only the ground ball number, you are taking away that ground ball that squeaks through the infield. SO it would just be converted to a fly out.

?