Improve conditions: Marchman: Rich Rundles has a posse

Rundlesfly-and-grounder problem?

The number of people who care about this is likely equal to the number of people who were excited to see Rich Rundles make the majors last year, but while reading the new edition of the Baseball Prospectus annual, I was a bit put off by this information on their new play-by-play defensive metric:

  The best PBP systems rely on highly detailed batted-ball data—a direction for where the ball was hit, some indication of how hard, and the result of the play, with the field broken down into many, many fairly small zons. That data is typically available only for the majors. To keep the majors and minors on an even setting, we’re dealing with a reduced set of data.

As I understand the idea here, BP wants to make apples-to-apples comparisons between their minor league and major league defensive numbers, and so is artificially crippling the data set they’re using to derive the major league numbers to bring it into line with the less granular data available for the minors. I see the appeal, but it makes the topline numbers suspect, especially when the system arrives at seemingly wonky results like Bobby Abreu rating as a plus defender and Hanley Ramirez as a Gold Glove candidate last year. Of course even very good systems have outliers, but not every system intentionally deals with a reduced set of data. For now I’ll continue to rely on UZR and Plus/Minus, though I’ll be curious to see what people like Tom Tango have to say about the technical pros and cons of the new system.

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