Jason Bay is now average defender

Los Angeles Dodgers at New York Mets
A little over a week ago fangraphs.com updated their UZR calculations with the first batch of 2010 data. This update included some work on arm skill as well as changes for quirky stadiums including Fenway Park. This change was done to include previous seasons and now Jason Bay made one of the largest gains as his -13.8 runs value became a 1.9 value. John Tomase decided to use this as a chance to say UZR owes Jason Bay an apology. Let's start with a reminder there is no chance the Red Sox are using UZR and have their own model so let's not make any assumptions UZR had anything to do with the Red Sox failing to sign him. Even with the changes no stat is perfect and I'm sure we'll be discussing the next Bay in the offseason. Perhaps that will be Jeremy Hermida who has improved his defense in UZR coming from Florida.
Los Angeles Dodgers at New York Mets

A little over a week ago fangraphs.com updated their UZR calculations with the first batch of 2010 data. This update included some work on arm skill as well as changes for quirky stadiums including Fenway Park. This change was done to include previous seasons and now Jason Bay made one of the largest gains as his -13.8 runs value became a 1.9 value.

John Tomase decided to use this as a chance to say UZR owes Jason Bay an apology.  Let’s start with a reminder there is no chance the Red Sox are using UZR and have their own model so let’s not make any assumptions UZR had anything to do with the Red Sox failing to sign him.  Even with the changes, no stat is perfect and I’m sure we’ll be discussing the next Bay in the offseason.  Perhaps that will be Jeremy Hermida who has improved his defense in UZR coming from Florida.

Let’s see if one year of average defense data makes Jason Bay suddenly a player the Red Sox should have gone to four years at $66 million.  His WAR in 2009 increased to a very solid 5.0 worth approximately $22.3 million last year.  That is impressive and moved him up to second on the team for position players behind only Kevin Youkilis who had a 6.0 WAR.

The first question is how solid is that UZR number?  Single year data is not very solid yet for UZR and it’s currently thought you need about three years of data to find a solid average.  That causes problems here as Bay had only played one year in Fenway where he was able to be an average defender for the first time in three years.  That could be partly explained by his knee troubles in 2007 as well.

So far in New York he has been average as well, although slightly negative, but minimally.  I’m fairly comfortable saying Bay would have been average for another year or two in Fenway and perhaps no more than 10 runs negative by year four of a deal to stay in Boston.

Assuming he doesn’t enter into the “old player skills” decline and follows a normal decline in his 30′s you should expect him to total WAR numbers of 4.5, 4.0, 3.5, 3.0 as the average decline is 0.5 WAR per season.  That gives him a total of 15 WAR in the next four years, ignoring the option year in 2014.

That is nothing to ignore as 15 WAR based on the value of a win above replacement previous to this offseason would be $67.5 million, but after this offseason it would be down slightly as many players found closer to $3.5 million per win.  That would make him worth closer to $52.5.

Based on these numbers Bay is someone who might have looked better to the Red Sox as a outfield and DH option.  His fielding is obviously better hidden in Fenway Park and with Ortiz up after 2010, he could have split time at DH when on the road.

There are still the injury questions raised by the team and his skills are that of an older player where it is hypothesized that these players will decline much quicker.  I can’t find any conclusive studies on this theory, but if his strike out rate stays above 30 percent then he will not follow the decline I outlined above.

Defense was not the reason the Red Sox got cold feet with Bay in my opinion.  Health and his skill set are the largest factor in a decision not to retain him for the next four years.

Check out the new blog/podcast from frequent commenter Aaron and writer at RotoSavants.com at http://historyoftheredsox.blogspot.com/

Categories: Boston Red Sox Jason Bay

After taking an interest in sabermetrics and statistical analysis Troy began trying to use it to an advantage in fantasy baseball. He started the website RotoSavants.com and also spent time at HardballTimes.com and FantasyPros911.com. After a few years the interest in the Red Sox drew him to start a Red Sox-oriented site (Yawkey Way Academy) with fellow writer Lee Perrault. A short time later he joined Fire Brand. Writer from: December 14, 2009 – July 24, 2010, March 3, 2011 – May 10, 2012.

8 Responses to “Jason Bay is now average defender” Subscribe

  1. Nick April 29, 2010 at 10:32 AM #

    ha ha ha ha ha ha ha ha ha

  2. aaron April 29, 2010 at 2:51 PM #

    At least you're only laughing instead of saying something irrational this time, Nick. I'm still waiting for you to respond to me on thehttp://firebrandal.com/2010/04/20/jd-drew-struggl… thread but I guess response to a reasoned disagreement isn't your style.

  3. Buzzy April 29, 2010 at 3:57 PM #

    This is meaningless (not Troy's point but the debate centering around UZR). The reason is that teams like the Sox don't use UZR anyway. The Sox have a ton of data on plays in LF of Fenway, and have their own, more accurate homebrewed versons of said metrics. Those metrics like do a far better job taking into account the type of balls hit at fielders and the normalization with respect to field geometry. The UZR debate is a scarecrow because the Sox most likely don't use UZR. The Sox took all of Bay's attributes into account (fielding as measured by a set of metrics that are likely not available on the web, health, age, skill-set) and made him an offer they deemed fair (and seemed quite fair). That was what they valued him at, and the Mets valued him more, so fine for them.

  4. aaron April 29, 2010 at 4:37 PM #

    I agree that it would be great to have access to the Sox metrics, which are probably better at judging Fenway than UZR is, but to say that because we don't have those data the debate is meaningless seems like quite the wet blanket. If we bought into that then we wouldn't ever be correct to analyze or second guess front office decisions. I guess that's one way to look at it but it seems like not much fun to me.

  5. Buzzy April 29, 2010 at 4:56 PM #

    What I am saying is that UZR did not factor into the Sox accessment of Bay and his defense. Furthermore, even with regard to UZR let's see with regard to Bay. He is a career bif minus in the outfield even after "correcting" for Fenway (I hardly call a career -55 an "average" fielder; for all we know his last year was like Jeter's last year in the field).

  6. aaron April 29, 2010 at 6:31 PM #

    Yeah, I agree that the Sox don't use UZR but that doesn't mean that we shouldn't use our best metric available to assess the situation on our own, does it? It seems like that's what you mean when you say it's "meaningless" but correct me if I misunderstand.

  7. TroyPatterson April 29, 2010 at 7:37 PM #

    The title was a bit of Snark I must admit. That was why I tried to remind everyone that one year of UZR data is dangerous. I look at UZR the same way I do with ERA before we had DIPS, FIP, xFIP, etc. It's nice, but we need to see much more data before making any conclusions.

  8. Buzzy April 29, 2010 at 8:37 PM #

    I mean "meaningless" with regard to old school/media types who argue that things like UZR are worthless-in this regard it is no pie of the face of the Sox management since they never ascribed to UZR's # in the first place. My own feeling for waht it is worth is that UZR is meaningful if used and viewed as a set of data (with flaws) taken over a large sample. Based on that, regardless of adjusting for Fenway, Bay is still a pretty bad defensive LF.