Taking the UZR Out Of Uzer Error

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On Monday I tossed off a quick link to a column by Smilin' Geoff Baker in the Seattle Times. I used it to make reference to the fact that Jason Bay's defensive skills may have been denigrated to the point where he's actually underrated in LF. Or at least not bad enough to the point where it had a major effect on his free agent value this offseason.

The column made a larger point of trying to dissect the usefulness of UZR (quick explanation here for those of you that just come here for my Bat Attack Roundups) in light of its often dramatic year-to-year swings for a player. It's a discussion I've had with Rob on occasion. Baker used Adam LaRoche as an example, I brought it up a couple weeks ago after a perusing of Jacoby Ellsbury's numbers. As Baker notes, even though park factor is accounted for in UZR it's hardly the most foolproof part of the metric. But, the more sound explanation for players having varied year to year numbers (especially when playing for the same team) is simply sample size.

With a typical outfielder getting at least twice as many plate appearances as he does defensive chances, when reading advanced stats we've all learned to trust a single season's offensive numbers to paint an accurate portrait of a player, but to factor 3 years of defensive numbers. It makes sense, but it doesn't solve the perception problem of simply looking at a guy's UZR numbers and trying to figure what kind of fielder he is right now. Common sense tells you that you can't simply average the numbers since each year will have a different number of defensive chances, and while the reality of a player that has posted a -14.2, +10, -6.9, +12.1 is that he's got average range and average arm, it doesn't look that way on the page.

So to solve the perception problem and stop dummies like me from misunderstanding/misinterpreting the meaning of UZR, I have a humble proposal. Do away with the year-to-year UZR rating of a player, and replace it with a single career number. Beginning in a player's second year the problem of small sample size will start to dissipate and on a single look you'll be able to make a quick judgement on just how much, or how little, he's able to do in the field. To account for diminishing skills with age or trouble playing in a new park, each player's career UZR can have a little up or down arrow like the Beckett Price Guides of old representing whether his number has gone up or down in his last 400 defensive chances.

I spent time last night investigating the calculation of UZR but since the last math class I took was something called "Math For Liberal Arts II" I didn't understand most of the mechanics. But I do understand the time and effort Mitchel Lichtman put into creating and revising the stat to factor in as much relevant information as possible about dudes goin' nuts in your outfield/infield. Like donning a mint condition vintage Garfield shirt on an important date, my suggestion is mostly an aesthetic one. But one that I think has some merit.


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13 Comments

I think ballpark adjustments are the most difficult aspect of defensive metrics. The last two guys to ply their trade in front of the Green Monster has terrible, awful numbers. Is that because balls that carom off the wall count as unplayable? There are so few opportunities for them to make + plays, perhaps it squeezed Manny and Bay.

Ellsbury will be a good litmus test has he's a fast guy who takes bad routes to the ball. There isn't much margin for error when the fence is 250 feet from the plate.

/dickjoke

I'm trying my best to find holes in Catshirt's argument and I cannot. Is it because he has postulated a sound statistical paradigm, or is it because all those math classes I took to fulfill my minor were worthless?

One great point: arrows are excellent graphical ways for us to easily understand how a player's career is progressing. Franklin Gutierrez: number two with a bullet!

DEATH TO FLYING THINGS

Mark Teixeira and Ryan Howard are another great example of the shortcomings of UZR. UZR (and UZR/150) has Howard listed as a better fielder than Teixeira but an appeal "to the eyes" would lead nearly everyone to say otherwise...

UZR hates first basemen.

I like the UZR solo but his best work was defintely with Wu Tang.

Am I the only one who is creeped out by the picture accompanying this post?

How does this relate to Jeter's terrible play? As we know, he is the ultimate "compiler" and therefore not eligible for the HOF. Now Brady Anderson, on the other hand...DOMINANT for a short period of time. That fits the criteria.

but an appeal "to the eyes" would lead nearly everyone to say otherwise...

It's that sort of bias that a stat like UZR seeks to destroy. Also, your inherent racism against big brown people.

Also, it looks like Kris' idea has inspired some other writers to come up with their own theses.

A baseball card reference? Followed by a Wu-tang joke? You people are just pandering to me at this point.

I got my UZR back
You stats is wack
face it Catshirt is back

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