The Biggest UZR: Pilot Episode

Defense...

The final frontier...

These are the voyages of the fielding metric UZR...

Its continuing mission - to seek out new skill and new abominations...

Boldly going... where no metric has gone before.

2009 is a remarkable year. For the first time, the system which many consider the best method for evaluating defense is freely available to the public. The metric is called Ultimate Zone Rating, and you can find it on Fangraphs. The accessibility of UZR allows us to pierce the veil of one of baseball's greatest mysteries: defense.

Defense is probably the hardest component of the game for fans to judge. There are several reasons for this. First of all, observation - watching the game - is mostly useless. There is simply too much information for a viewer to process and remember to evaluate defense objectively. Furthermore, it's human nature to emotionalize memory. A disastrous throw by Julio Lugo outweighs all the grounders he gets to with his speed; a gliding play by Jeter lingers in one's mind longer than all the easy liners that pass by him.

Secondly the best statistics to look at defense are not well known or widely available. Most fans get their baseball information from television broadcasts, where they only hear about error totals and fielding percentage, when they hear defensive stats at all. Those measures tell them very little about a player's true defensive value. Great fielders not only execute catches and throws, they also get to more balls than their peers and turn well-hit balls into outs. 

Thirdly, fans tend to view defensive skill as a mostly static quality. Many of us, myself included, form judgments about players' defense, and then assume it to be the same every year. Back in 2008, I thought: "Coco Crisp has great speed and makes phenomenal catches, and his defensive ratings were great last year, so he must be a good defensive player this year, too." Unfortunately, players' defense can vary from year to year as much as their offense. For example, Crisp was amazing in 2007, but his 2008 was a real step back. It's much easier to see this with UZR: in 07, Crisp had a career-high UZR of 24.4 at center field, meaning he saved 24.4 runs above an average defender; in 2008, his UZR fell to -8.6.

Finally, for those people who want to study fielding, there's the hurdle of finding, understanding and evaluating the advanced systems. You get a veritable alphabet soup of systems and stats: Range Factor, ZR, RZR, RAR, and UZR. And many of the best stats, including, until recently, UZR, are proprietary information unavailable to fans. Worst of all, the stats can sometimes paint dramatically different pictures of players, meaning you have to either reconcile or ignore certain stats. You don't have to be a math nerd to study sabermetrics, but it probably helps.

The purpose of this column is to track Red Sox defense as the season goes along, using UZR. Why UZR? Well, it's regarded as one of the best fielding metrics, and it is freely available to the public. Why track it? Well, it gives an excuse to talk about defense in general, and it gives us a chance to see how player's performances affect overall numbers.

So enough talk, on to the numbers:

Overall, the Sox are the 7th worst team in MLB by UZR, at -16.5. This is not as bad as it sounds, because the team's been climbing in the ratings, thanks to better defense. IIRC, they were 2nd worst not too long ago. Let's look at the individual players with a minimum of 15 games at a position:

The Good:

Dustin Pedroia 2B 5.0
J D Drew  RF 5.0
Nick Green SS 3.3
YOUUUUUK 1B 3.1
Mark Kotsay 1B 1.5

Four of eight positions have above-average defenders. Pedroia and Drew are the cream of the crop, with Green and Youk not far behind. Green's come a long way since the beginning of the season, where his UZR was negative and he committed 9 errors. To the casual observer, he's played better of late, showing great range, making strong throws to first and committing fewer errors. Unfortunately, our best defenders don't make up for the worst ones.

The Bad:

Youkilis 3B -0.5
Rocco Baldelli RF -3.9
Jacoby Ellsbury CF -6.4
Julio Lugo SS -6.8
Jason Bay LF -7.8
Mike Lowell 3B -8.0

The big surprise here is Ellsbury, who I think most of us would expect to be superb in center. He's agile and can make great catches. Lowell's aging and dealing with injury, Bay has never been a good defensive left fielder, and the less said about Lugo, the better.

The Biggest UZR:
Julio Lugo SS at -6.8 (-38.6 per 150 games, worst among regular starters, including Bay and Lowell)