Sabermetrics: FIP

In honor of last week’s almost perfect game by Dodgers lefty Rich Hill, I decided to dedicate this week’s sabermetrics post to FIP (Fielding Independent Pitching), which was created in order to predict the ability of a pitcher to prevent runs independent of the actuality of his team’s fielding. The stat bases itself on league averages of balls in play–or the average potential of a fielder to make an out on a ball that should be an out–as pitchers have no control over the abilities of their fielders, and can sometimes be  penalized by shortcomings of their defense. FIP attempts, in one statistic, to rectify that fact.

I’ll allow the FanGraphs graphic to illustrate the specific formula used to calculate FIP:


FIP looks like ERA, and can even be measured on the same scale–though there is some controversy over whether or not FIP should have been manufactured to use the same scale as ERA in the first place. Often, a given pitcher’s ERA and FIP are similar; or at least, they start out that way at the beginning of the season. Variance occurs between the statistics–a.k.a. ERA begins to climb–depending on luck of where the ball lands, or luck of the talent of fielders behind the pitcher. Variance can also occur depending on how good a pitcher is in the stretch–that is, depending on the pitcher’s capability of preventing successful stolen bases while he is on the mound. Even generating more easily-catchable pop-flys than line drives or grounders can cause variance, as pop-flys are easier outs than these other types of hits.

It is important to remember that, unlike ERA, which is a measure of the past, FIP is a good indicator of how a pitcher will fare in the future, because it takes approximately an entire season for FIP to be accurate measure of performance. Therefore, FIP isn’t always the best indicator of a pitcher’s performance early in the season or their career.

Like ERA, an excellent FIP is considered to fall around 3.20, with the league average around 4.20. Rich Hill’s FIP, for example, is currently 3.94 for the 2017 season, with a slightly lower ERA of 3.71. His career average FIP is 3.95. So in theory, an event like the third base error that cost Hill his perfect game last week, should not factor into FIP. However, because the Dodgers currently have one of the top 10 defenses in the Major Leagues–at least in terms of fielding percentage, or how often the defense successfully makes an out–it is understandable that Hills’ FIP as a Dodger would be slightly lower.

It is unlikely that any pitching statistic completely overrides ERA; ERA will always be the easiest and most common way to introduce and assess a pitcher. But in the age of sabermetrics, it is also important to consider other stats, such as FIP, that are better indicators of performance unaffected by factors that may be out of the pitcher’s control.

Even though, of course, those isolated performances exist in an alternate universe–the same universe where Rich Hill was able to pitch that perfect game.