Saturday, January 24, 2004

Well, unfortunately I've been idle with my writing for over a week, but that doesn't mean that I haven't been working on my analysis. I've been looking at player evaluation methods for almost the past year now, including reading Bill James' magnum opus Win Shares, and I'm convinced that this is the most thorough player evaluation method available for several reasons.

First, it is the only method that breaks down total player contribution to his team's success by dividing "Win Shares" between pitchers, fielders, and batters in direct proportion to the number of games the team has won. The only other method, that I am aware of, that considers fielding is Pete Palmer's Linear Weights System.

Second, Win Shares is the only method that considers a player's ability to be good enough to earn major league playing time as a positive value. The Linear Weights System uses a zero value as its starting point, with each player's contribution measured as either a positive or a negative from this base point. In other words, a player who is good enough to earn considerable major league playing time, but is rated below average by this system, actually earns a negative value. On the other hand, a player who sits on the bench (i.e. doesn't play at all) remains at a zero value. In fact, Steve Garvey rates as -5.2 for his career. This is absolutely ridiculous. Even those of us that suspect, or are convinced, that Garvey is overrated would never even suggest that he was a below average player and that the composite value of his career was a negative. This would suggest that he actually hurt his team more than he helped it, which is a ludicrous notion.

Third, I am convinced that James' system does the most thorough job of building in adjustments for such contextual factors as the era in which a player performed, the contributions of the players on the teams for whom he played, the strength of the competition, and the ballparks in which he played. Linear Weights considers these factors, but I've already pointed out its major shortcoming for which I'll admit to being completely unforgiving. All other player evaluation methods are essentially offensive-oriented systems that express performance on a rate basis, and do not make these important contextual adjustments.

I probably should explain what I mean by "express performance on a rate basis". Batting average is the most basic example of a statistic that measures performance as a rate. There is no consideration given to the player's ability to accumulate statistics. In order to evaluate a player's career, or to compare the careers of several players, we must consider both types of statistics, rate stats and cumulative stats. By doing so, we assign value to both the player's overall ability to perform and his ability to earn playing time, a significant factor of which is his longevity.

There are many rating systems out there that have done an excellent job of expanding on the shortcomings of batting average as a way to evaluate players. OPS (on-base percentage plus slugging percentage) is a simple, but fairly effective, way to measure a player's overall offensive ability. Other much more complex methods have been developed, but they are all offensive rating systems that are only effective at measuring a player's ability in a given season, or across a few seasons, because they do not place any weight on cumulative statistics. They are not designed to do so, and, therefore, are not as relevant to evaluating a player's overall career as the Win Shares system is.

The next part of my analysis will be to compare these four players using the Win Shares system. Despite my endorsement of Win Shares as the ultimate player evaluation method, there still are several ways to use the system to compare players. I'm not just going to state that Tony Perez earned 349 career Win Shares to Keith Hernandez's 311, Steve Garvey's 279, and Don Mattingly's 263, and, therefore, Perez is the best, Hernandez the second best, etc. I'll compare them using a few Win Share rate statistics as well, although their cumulative Win Shares certainly will be taken into consideration as a major factor.

For more information on the Win Shares system, you'll have to locate a copy of Bill James' book, Win Shares. Unfortunately, it's already out of print, so you'll have to look for it at your public library or try to find a used copy on the Web. Pete Palmer's Linear Weights System is explained in detail in Total Baseball: The Official Encyclopedia of Major League Baseball. Other statistics, such as OPS, on-base percentage (OBP), and slugging percentage (SLG), are explained in detail in the Batting Stats Glossary at

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