UZR and Jason Bay

Today the Boston Herald and Deadspin homed in on Jason Bay’s 13-run change in his 2009 UZR. John Tomase of the Boston Herald writes that “UZR owes Jason Bay an apology” and Deadspin’s Barry Petchesky writes that “it’s foolish to jump aboard the Sabermetrics bandwagon.”

John Tomase goes on to say:

… Ultimate Zone Rating, which was treated as Gospel this winter during all the discussions of defense around these parts.

Let’s just say that it’s not UZR’s fault that it’s been treated like gospel, and anyone who actually reads FanGraphs should know that we definitely don’t treat single-season UZR like gospel either. Dave Cameron addressed “not liking or agreeing” with UZR last year in his Bay vs Cameron article and Jack Moore consulted multiple defensive metrics in his contract analysis of the Jason Bay signing.

Even with the UZR improvements, Bay is still listed as -35 runs below average since 2007. Some will point to his poor 2007 as the result of still recovering from knee surgery, but his problems in the outfield continued to plague him in 2008 between playing in PNC and Fenway.

All the other defensive metrics seem to agree that he has been pretty sub-par since 2007 as well. John Dewan’s +/- has him at -18 runs. Sean Smith’s Total Zone has him at -47 runs and Brian Cartwright’s WOWY based system likes him the best at -8.2 (having him at +9 in 2009).

Now there’s no doubt that, in 2009, it seems most systems have him somewhere around average, which is a fairly large departure from his 2007 and 2008 metrics, but let’s not forget that the fans themselves seemed to think Bay was below average in 2009. Tom Tango runs the Fans Scouting Report each year and they rated Bay a 2.69 on a scale of 1-5, which placed him 48th of the 71 rated left fielders.

Do we need to average out every single defensive system for each player to get a decent picture of his defensive abilities? Probably not. But when in doubt (like some of you were with Jason Bay), you can always get a second opinion, and a third opinion. Right here on FanGraphs we now carry two separate defensive systems (UZR and John Dewan’s Defensive Runs Saved) for all players.

Baseball statistics can be a valuable tool in your toolbox when analyzing a player. Often times they can be one of the most useful tools in your toolbox, but there’s really no reason to throw that tool away completely, just as you wouldn’t throw away scouting information. And as I’ve said before, a lot of times the metrics you use actually do contain “scouting” information.

New information and better models are coming out all the time and this is not unique to baseball. Analysts use the information that’s available to them and in light of new information, there’s a chance that the previous analysis might be wrong.

But the alternative as Barry Petchesky wrote is that “it’s foolish to jump aboard the Sabermetrics bandwagon.” Suppose we go back to the days of batting average and fielding percentage; to how many players would batting average or fielding percentage “owe an apology”?

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David Appelman is the creator of FanGraphs.