Thursday, December 15, 2005

Win Shares Walkthrough, pt. 1

This series will be a (hopefully) complete walkthrough of the Win Shares method, similar to that done by Bill James in the Win Shares book. Since James already did this in his book, and since he is the creator of the method, you may ask, why is it necessary for you to do it again? The reason why I am doing it is so that I can comment on what I think are the flaws in Win Shares at the actual stage of the method at which they occur. This way it is easier to see what I mean rather then running through the method, then making a laundry list of complaints at the end.

In the past I have probably been a little too tough on Win Shares. Bill James is a brilliant sabermetrician who has contributed many great things to the field. Win Shares is not, in my opinion, one of those, but it certainly had a lot of work behind it, I’m sure that Bill felt that the assumptions he made were justified, and that he tried to create the best possible method he could. But I simply do not believe that Win Shares taken as a whole is a step forward for sabermetrics. The are of Win Shares which James takes most pride in is the fielding system he developed, which first credits the team fielding as a whole and then distributes the team fielding Win Shares to fielding positions, and then finally to individual fielders. Coincidentally, fielding statistics are the area of sabermetrics that I am least qualified to comment on (if you consider me qualified to comment on any). So the fielding system may well be a conceptual breakthrough, although again I have my doubts.

So this will not be a perfectly balanced assessment. I will admit that I have been a critic of Win Shares since it was first published and you should keep my point of view in mind as you read. I think that my criticisms are valid and based on solid reasoning, but one cannot completely divorce ones prejudices from their analyses.

So I will do this in several installments, and I will calculate the Win Shares for the 1993 Atlanta Braves, who won a classic pennant race against the Giants but were defeated in the NLCS by the Phillies. At various times I will slightly deviate from James’ official method. One example is that James rounds off all Win Shares to even numbers. I will maintain fractions throughout the process. I will attempt to note these departures as I come to them. I have only attempted to use and explain the post-1987 formulas here. I have rounded numbers in the explanation that I have not rounded on my spreadsheet, which will result in some rounding discrepancies.

I have tried to run through the procedure without giving my opinion and then have a “My Take” section which gives my opinion on the formulas I just reviewed.

A very important note before we start: this walkthrough should not be viewed as a substitute for reading James’ explanation of his method. First of all, any discrepancies between my description and his are obviously wrong here, since he designed the method and knows what he’s doing. Secondly, it would be best to read his first and draw your own conclusions and consider his arguments as you go and then read my interpretation. Also, his explanation is much more complete in many areas, while mine does not so much describe how each part is done or why but whether or not I think it is the right thing to do. So this is more of a commentary, where his is an explanation and a commentary.

The first actual piece should appear tomorrow; it will cover park factors and assigning win shares to team offense and defense.

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