The Ultimate Zone Rating

The latest thing in baseball is to emphasize defense.  And to help make that happen, baseball statisticians have figured out a way to quantify a player’s defensive performance, coming up with the counterpart to batting average called “Ultimate Zone Rating.”  Here is how it is calculated (though, as the article goes on, other factors, such as the specific ballparks, fly balls or grounders, etc., are also factored in):

So how does one arrive at a player’s Ultimate Zone Rating? Well, by far the easiest way is to let sabermetricians, such as those at the Web site http://fangraphs.com, do the hard work for you. But here is as simple an explanation as we can manage of the process that results in UZR.

First, take one ballpark, and dice it. Actually, sabermetricians use a standard model for all baseball fields, then they slice that into 78 zones. Partly because all real ballparks have different dimensions, they use only 64 of these zones in their calculations. Each position is considered responsible for a few of those zones.

The next step is to take the total number of balls put into play into each zone and divide it by the total number of outs recorded in each zone (with some modifications), thereby getting a league average. Then one does the same on an individual basis, looking at a given player’s rate of recording outs on balls hit into zones that are considered his responsibility. If that player’s rate is higher than the league average, he will have a positive (i.e., good) UZR.

via Ultimate Zone Rating is a tricky calculation – washingtonpost.com.

Here are some UZRs of current players.