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Question about defense independent pitching stats
Posted: 17 November 2010 07:35 PM   [ Ignore ]

Why do these metrics use components in which IP is the denominator, rather than total batters faced? E.g., for the strikeout component of FIP, the goal is to measure a guy’s propensity for striking batters out, not his propensity for striking batters out in relation to the outs he records, no?

If two guys strike out the side, but Pitcher A allows no batters to reach base and thus faces three batters, and Pitcher B allows 12 singles in between the strikeouts and thus faces 15 batters, why should their ability to strike people out be expressed as being equal? Same with BB and HR allowed.

Posted: 17 November 2010 08:08 PM   [ Ignore ]   [ # 1 ]
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Posted: 17 November 2010 08:08 PM   [ Ignore ]   [ # 2 ]
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http://www.insidethebook.com/ee/index.php/site/comments/sabre_nerd_fip_fight_ip_or_pa_maryann_or_ginger_a_primer_on_creating_a_metr/

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You don’t give up.  You should, but you don’t.

Posted: 17 November 2010 08:22 PM   [ Ignore ]   [ # 3 ]
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Purely guessing, from the seat of my pants.

One of the things that a formula like DIPS ERA is doing (because it was developed as a predictive tool rather than a method to analyze performance) is predicting BABIP or $H or whatever you wish to call it.  What such a figure “should be”.  This is implicit in that DIPS ERA does.

The reason why (in my view) H or BABIP or $H or what have you isn’t needed in the DERA formula, and why it doesn’t improve the predictive power of it when it’s included, is that K rate (supplemented suitably by HR rate and a bit by walk rate) is a better predictor of future BABIP or $H, than BABIP or $H itself.  Guys who are difficult to hit are, shockingly enough, difficult to hit.  (This is the point that 90% of the research on hit rates and BABIP has ignored… yes pitchers differ in their abilities to lower BABIP; it’s just that those pitchers are roughly ordered by K rate, suitably expressed).

But what K rate to use?  K/IP, which is roughly measuring K/AO, is likely a better overall predictor of BABIP than K/PA, because it hauls the outliers in.  Guys who are very BABIP-lucky (from good luck or good defense) will have a better relative K/PA than K/AO.  Guys who are very BABIP-unlucky (from bad luck or bad defense) will have a better K/AO (relatively) than K/PA.  So K/AO will probably work better as a measure of strikeout ability as it relates to its prediction of $H or BABIP.

This is what I believe - it may not be true, but it is the explanation that best fits (in my view) with all the research I’ve seen on this topic.

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