What The UZR Disciples Wont Tell You About Jason Bay

An article by posted on December 30, 2009

Keith Law of ESPN, a disciple of advanced metrics, says that Bay’s defense will dictate whether the contract is a good one or not. Umm, really?

Did Mike Piazza’s defense dictate whether his time with the Mets was good or bad too?

Of course Law, a long time proponent of advanced metrics, was alluding to the debate emerging over Jason Bay’s UZR or Ultimate Zone Rating. It’s a stat that assumes how many balls a fielder should get to based on those hit in his area of responsibility.

What you won’t hear about UZR is how dramatic the fluctuations are from year to year and what a poor indicator it is in determining a players present day fielding value. The notable Bill James once said,

“The interesting question is why defense is so much more difficult to quantify than offense in all sports. Perhaps defense by its nature involves more interaction between individuals than individual actions, and perhaps the way to get past that is to embrace the concept and measure combinations of players.”

In other words, put a player like Jason Bay next to a player like Carlos Beltran and it changes the whole ball of wax.

I did some research on the matter…

Last season Raul Ibanez was signed by the Philadelphia Phillies to play left field. The move prompted an outcry among all the stat-heads who pointed to Ibanez -23.5 UZR in 2007 and -10.5 in 2008. However, when coupled with gold glove centerfielder Shane Victorino, Ibanez posted an incredible 10.7 UZR or to better illustrate, a 200% improvement over the prior season. By the way, see what I mean about the wild fluctuations which make UZR so unreliable and flawed?

Anyhow, it’s Jason Bay’s -11.2 UZR that seems to be at the crux of the matter with those shedding tears over the Mets’ new leftfielder.

As difficult as this might be, amid the overwhelming and resonating sentiment that Jason Bay a terrible left fielder, consider the following facts I sought out and now present to you…

What the UZR disciples won’t tell you about Jason Bay, is that despite logging over 1,270 innings in one of the most difficult left fields in baseball, Fenway Park, Bay committed no errors in 2009 and had a fielding percentage of 1.000%. Mets left fielders committed seven errors in 2009.

What the UZR disciples wont tell you about Jason Bay is that his range (2.29 vs 2.12) and range factor per game (2.17 vs 1.80), were both far better than the average of all left fielders. 

What UZR disciples wont tell you about Jason Bay is that last season he had a career high 15 assists to lead both the American and National Leagues, and that seven of those were runners he threw out at home plate and third base. Those 15 assists were more than Carl Crawford and Matt Holliday combined!

In the not so very old days, long before UZR was invented in 2003, would there be any arguing about Jason Bay’s defense in left field based on his performance last season? I would actually bet that there would be more gloating than anything else.

Are we supposed to simply throw away over 100 years of what have long been considered the best fielding measurements in baseball because of a new statistic that has hardly stood the test of time?

UZR has less then a decade worth of data, an incredibly short track record of success for a group that is always harping on sample sizes, and has mostly shown that its fluctuations can dramatically skew the evaluation process of a player’s defense both negatively and positively.

I’m not suggesting that we discard or overlook the value of UZR, but instead I say we should consider it along with all of the other defensive measures that have worked so well for over a century.

I think it’s rather absurd to simply wipe out what would otherwise be considered a solid defensive resume all in the name of one new and very imperfect statistic.

The Mets got themselves a heck of a left fielder in Jason Bay. His 2009 Silver Slugger Award was earned for being the best offensive left fielder in the American League. His defense may not invoke memories of Barry Bonds in left field, but let’s ”stop” making a mountain out of mole hill, and lets “start” giving the Mets their due credit for a change.

About the Author ()

I'm a lifelong Mets fan who loves writing and talking about the Amazins' 24/7. From the Miracle in 1969 to the magic of 1986, and even the near misses in '73 and '00, I've experienced it all - the highs and the lows. I started Mets Merized Online in 2005 to feed my addiction and interact with other passionate Met fans like you. Follow me on Twitter @metsmerized.

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