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Monday, September 19, 2011
Tennis/golf rankings… for pitchers!
I’ve always been fascinated by the world rankings for tennis and golf. I was especially interested in Serena being ranked #28 for the US Open. The best way to see how a system works is to look at extreme cases. So, if someone doesn’t play for a period of months or longer, how does that effect the ratings? How far back of performances do you consider?
Basically, this is day-by-day Marcel for tennis and golf. I have no idea how they calculate things. Presumably Chess rankings are similarly affected, though presumably it won’t need to rely so much on recent data.
Bill James wondered: well, why not for starting pitchers? And he proposes a system that is simple enough: start everyone at some baseline that you can’t get below (he uses 300), and then remove 3% of his score entering a game, and add in 30% of his Game Score. Then a daily penalty for missing a start over more than 7 days, and yet another penalty for missing a start more than 200 days. All very sweet.
I’m not sure it works with those particular numbers, but, the basic framework seems good enough.
Basically, this is day-by-day Marcel for starting pitchers, but without being so computational heavy like Marcel.
In my view, the best way to test James’ particular implementation is against the daily Marcels.
***
This is how James’ system sees the rankings for #1 over the past two years:
Tim Lincecum August 1, 2009 to September 6, 2009
CC Sabathia September 7, 2009 to September 13, 2009
Tim Lincecum September 14, 2009 to September 18, 2009
CC Sabathia September 19, 2009 to September 30, 2009
Tim Lincecum October 1, 2009 to April 15, 2010
CC Sabathia April 16, 2010 to April 19, 2010
Roy Halladay April 20, 2010 to May 3, 2010
Tim Lincecum May 4, 2010 to May 17, 2010
Roy Halladay May 18, 2010 to September 22, 2010
Felix Hernandez September 23, 2010 to October 5, 2010
Roy Halladay October 6, 2010 to July 30, 2011
Justin Verlander July 31, 2011 to the present
So, Lincecum and CC trade off the #1 spot for a few months, then it’s Halladay with some blips from Lincecum and Felix, and then Halladay keeps control until Verlander.
Like I said, I like the basic premise of it. Now it’s just a matter of whether everything is as balanced as it should be.
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