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Better Know a Stat- Fielding Independent Pitching (FIP)

For the second installment of the TBLA "Better Know a Stat" series, I wanted to take a look at the pitching statistic which attempts to isolate the pitcher’s responsibility for the runs allowed using only walks, strikeouts and homeruns. 

The FIP formula is (HR*13+(BB+HBP-IBB)*3-K*2)/IP, plus a league-specific factor that scales FIP to match league average ERA for a given season and league.

Note: The league specific factor I have used for FIP in the past is 3.20.

The basic argument for using FIP as opposed to ERA and WHIP is the realization that the pitcher has very little control for where the ball goes once it is hit by the batter.  As I’ve watched baseball, its easy to notice that some times the ball is struck well yet right at a fielder, whilst other times the ball appears to be a routine inning ending double play, only to find the baseball rolling past Jeff Kent playing second base.   As a result, a pitcher with a better defense behind them will be less likely to surrender hits (and ultimately runs) than the pitcher will the below average defense. 

FIP only penalizes or rewards the pitcher for completion of the Three True Outcomes (TTO), the home run, the strikeout and the walk (not including intentional walks.)  The strike out is the pitcher winning the individual battle between the pitcher and batter, while the walk and the home run are the results of the batter winning the plate appearance.  All other outcomes are impacted by the defense, and therefore impossible to isolate the level of responsibility that should be bourn by the pitcher as opposed to the defense behind them.  In contrast to the first entry in the "Better Know a Stat" series, where OPS+ is a combination of statistics, FIP rejects several plate appearances that don’t result in the TTO in order to isolate pitching contributions. 

I find FIP to be particularly important when judging minor league pitchers and potential trade and free agent targets. Minor league fielding is so erratic, that it’s certainly a best practice to ignore defense altogether. While an argument could be made that at least all major league fielders are somewhat decent, minor league deficiencies in the field is too significant to be ignored.  Additionally, when playing arm chair GM (as we may do on TBLA from time to time), its best to give less weight to ERA or WHIP than FIP, because the ERA and WHIP are impacted by the team defense, a defense which the potential target will not be bringing with them.

One could argue that FIP is less important when comparing pitchers from the same staff. Clayton Kershaw, Chad Billingsley and Randy Wolf all pitched for the Dodgers; therefore the defense behind them should be relatively constant.  While true to an extent, lineups change (Casey Blake is a much better third baseman than Ronnie Belliard) and parks change (certain parks benefit the pitchers by having more foul territory.) The biggest drawback to FIP is that it treats all homeruns the same way, regardless of it the home run was hit in Colorado or San Francisco.  On my next installment of the series, I will discuss how x-FIP attempts to address that issue.