Comments on: Should Defense be More Consistent than Offense? http://www.baseball-reference.com/blog/archives/14730 This and that about baseball stats. Tue, 16 Jul 2013 17:01:55 +0000 hourly 1 https://wordpress.org/?v=4.6 By: Johnny Twisto http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-150243 Mon, 12 Sep 2011 04:59:24 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-150243 No, clearly players have different fielding abilities between them. I am talking about the variation within a player. According to FG UZR Curtis Granderson is amongst the worst CF this year. Last year he was one of the best according to them. He looks the same to me. He doesn't seem to be hurt. Why the variation? I think it probable that the same player is playing at the same level and the difference is error in measuring it.

(You'll probably never read this, but....)

...this is an example of why people reject defensive stats without cause (and should not). *Because* defensive stats are historically so inconclusive, fans assume they mean little and assume players have a defensive ability which changes little from year to year. How did Curtis Granderson go from +31 and +20 runs batting in 2007-8 to -2 runs batting in 2009? I'll guess a lot of Tigers fans thought he looked the same. (Or if they picked out differences, it was likely ex post facto, because they "knew" he was performing worse, because offensive numbers are more detailed and accurate.)

Without more information, it would be very easy to say a batter is probably "playing at the same level and the difference is error in measuring it" if you saw him go +31, +20, -2, +4, +32. That's Granderson's batting performance (per WAR), but it's not dissimilar from defensive numbers which cause some to dismiss said defensive numbers. We accept the inconsistent offensive numbers because we have more evidence those things actually happened. We shouldn't automatically dismiss the defensive numbers because they are inconsistent.

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By: Matt http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-148756 Fri, 09 Sep 2011 15:40:25 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-148756 While it's a decent comparison, Brooks Robinson did have WAR near 70 (69.1), whereas Jones' is 60(60.1). In the WAR-world, 60 is borderline HoF, whereas near 70 is basically a lock. The difference in WAR can be mostly attributed to Brooks maintaining for longer than Jones did....of course the eras were completely different as well. Yes, WAR tries to account for differences in era, but Brooks played most of his years in the second dead-ball era, whereas Jones played in an inflated offensive era tainted by steroids.

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By: Thursday Links (8 Sep 11) | Ducksnorts http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-148150 Thu, 08 Sep 2011 13:37:08 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-148150 [...] Is WAR the new RBI? (It’s About the Money, Stupid). This looks like an interesting read, if a bit long (nearly 2,400 words). Rob Neyer offers his critique, while Sean Forman has questions of his own. [...]

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By: Jason http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-148012 Thu, 08 Sep 2011 05:14:38 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-148012 Twisto,

As far as I can tell, the data is not available on the site for me to do it. If the data were available, it would be pretty straightforward to do with software such as R (http://www.r-project.org/).

No, clearly players have different fielding abilities between them. I am talking about the variation within a player. According to FG UZR Curtis Granderson is amongst the worst CF this year. Last year he was one of the best according to them. He looks the same to me. He doesn't seem to be hurt. Why the variation? I think it probable that the same player is playing at the same level and the difference is error in measuring it.

I really do think much of the difference in defensive statistics is error. I think the error in the measurement is probably on the same order as the differences we are trying to measure making the enterprise entirely misleading. I want to know if a player with a UZR of 20 is really better than a player with a UZR of 10. If the confidence intervals of both measures largely overlap then we should regard the differences as insignificant.

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By: Johnny Twisto http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-147999 Thu, 08 Sep 2011 04:06:08 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-147999 I read the article on bootstrapping, or rather, I tried to read it. It's mostly Greek to me. I've never taken any courses in statistics. I'll give it another shot later.

I think Sean Forman was a mathemathics professor -- if you're still hanging around this thread, can you bootstrap the TZ numbers and tell us what you find? And what it means?

Or Jason, can you do it, in Excel or something? Is the data you need available on B-R?

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I'm not sure if I completely understand what you're asking in #50. It sort of reads like you think the differences in defensive ratings are (at least mostly) due to measurement problems. I don't deny that measurement problems exist. But do you think every major leaguer has essentially the same defensive ability? I doubt you do so I'm assuming I'm misunderstanding you.

Sorry if I'm coming off as a dunce.

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By: Jason http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-147985 Thu, 08 Sep 2011 02:48:35 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-147985 Twisto,

So there is pretty much no variability in the balls a player gets to. They almost always make the play. All of the variability in the widely variable defensive stats must then come from their ability to get to the ball if we are to believe that the variability is real and not simply a measurement problem. But why should we believe this is the case?

Sometimes players aren't quick enough and sometimes they are to get the exact same ball? Or maybe the ball that is rated as exactly the same actually isn't. Or maybe its both. What do you think?

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By: Johnny Twisto http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-147981 Thu, 08 Sep 2011 02:16:56 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-147981 Is the old Zone Rating still tabulated? On ESPN.com maybe? There you'll see your spread. I believe it is a simple division of plays made divided by all balls in the player's zone. No one's close to 100%, and the results wouldn't be all packed together like fielding %.

The more modern stats generally take the same approach, they've just converted the results into runs saved above or below average.

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By: Johnny Twisto http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-147979 Thu, 08 Sep 2011 02:12:30 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-147979 Isn't catching the balls they get to the very definition of repeatable? They pretty much make the play every time.

Right, except for the ones they don't. See Aweb's #23. And also, fielding % is only based on chances, whereas so much of defense is about balls *not* reached, which don't show up as chances.

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By: Raphy http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-147970 Thu, 08 Sep 2011 01:54:22 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-147970 Sean - Do people expect "greater consistency on defense than on offense" or an equivalent.

While offensive numbers fluctuate, generally there is a fairly predictable progression of offensive statistics throughout a player's career. I have not spent a lot of time on defensive stats (I'm still waiting for that PI you promised.), but my impression is that there is a lot less predictability in the overall fluctuations.

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By: Jason http://www.baseball-reference.com/blog/archives/14730/comment-page-1#comment-147963 Thu, 08 Sep 2011 01:12:36 +0000 http://www.baseball-reference.com/blog/?p=14730#comment-147963 Sean,

Isn't catching the balls they get to the very definition of repeatable? They pretty much make the play every time. ....on the other hand, even the best hitters hit foul balls, grounders and pop ups in batting practice (let alone when the pitcher is trying to get them out!). ...hitting is really, really difficult. Fielding, not so much.

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