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Bill James revising split of offense and defense in Win Shares

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  • Bill James revising split of offense and defense in Win Shares

    For those of you who are not aware, Bill James has been working on a revision of Win Shares. For the most part the big difference is in the introduction of Loss Shares. He has been slowly leaking tidbits at his new website Bill James Online.

    Today he provided a short article in response to a question that was recently asked about the decision to allocate 52% of credit to pithcing and defense and 48% to hitting and baserunning. The article states that this decision was ultimately driven by the way that he had accounted for a pitcher's hitting. Basically he had taken positive runs created by a pitcher's hitting and credited those runs to the pitcher's run prevention.

    He now admits that this was a mistake that he is fixing in the next version. Here's a short blurb...

    Early on in the design of Win Shares and Loss Shares I realized that, using 52% for pitching and defense, I had too many Win Shares going to pitching and defense, and I needed to move it back to 50%. So then I asked myself, “Well, what am I doing different here than I was before, that caused this problem to go away?”

    Just a silly design mistake on my part.
    Well, that makes me feel a little better. The whole 52/48 thing really bothered me, as I thought the original explanation was somewhat lame. Along with the introduction of Loss Shares, I think we're seeing a little progress here. We'll have to wait and see what else is going to be fixed.

  • #2
    So far, he's hit on two of the things that were big problems. Another one is that starters are very undervalued.

    The split of fielding/pitching done at the team level rather than the correct pitcher level.

    He's also allowing for negative WS and negative LS.

    Really, there were alot of problems with WS, and many of us detailed them, and Bill seems to be finally getting around to fixing them.
    Author of THE BOOK -- Playing The Percentages In Baseball


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