THE BOOK--Playing The Percentages In Baseball

Monday, March 17, 2008

New-age FIP

I don’t remember if I linked this ever, so I’ll do so now.  I can’t tell right now if he’s handling the out issue properly (is he using regular IP, or adjusted IP?), etc.  The basic form is the following:
+1.40 runs: any homerun
+.33 runs: any walk, hit batter, line drive
-.10 runs: anything else
-.30 runs: any strikeout, infield popup

For your average pitcher per 9 innings, you’ll have something like one homerun, 9 walk-types, 9 strikeout types, and 20 other PA.  That gives you roughly 0 runs relative to average (someone here can give you more precise numbers).

The main point I want to bring out is that if you want to extend FIP, you can throw in infield popups with your strikeouts, and your linedrives with your walks, always following the form of:
(13*HR + 3*BB - 2*SO)/IP + constant