Fielding Independent Pitching (FIP) measures what a player’s ERA should have looked like over a given time period, assuming that performance on balls in play and timing were league average. Back in the early 2000s, research by Voros McCracken revealed that the amount of balls that fall in for hits against pitchers do not correlate well across seasons. In other words, pitchers have little control over balls in play. McCracken outlined a better way to assess a pitcher’s talent level by looking at results a pitcher can control: strikeouts, walks, hit by pitches, and homeruns.
A walk is not as harmful as a homerun and a strikeout has less impact than both. FIP accounts for these kinds of differences, presenting the results on the same scale as ERA. It has been shown to be more effective than ERA in terms of predicting future performance and has become a mainstay in sabermetric analysis.
For those curious, here’s the formula for FIP:
FIP = ((13*HR)+(3*(BB+HBP))-(2*K))/IP + constant
The constant is solely to bring FIP onto an ERA scale and is generally around 3.20. You can find historical FIP constant values here, or you can derive the constant by taking league-average FIP and subtracting that from league-average ERA.
Please note that the following chart is meant as an estimate, and that league-average FIP varies on a year-by-year basis so that it is always the same as league-average ERA. To see the league-average FIP for every year from 1901 to the present, check the FanGraphs leaderboards.
Things to Remember:
● Voros McCracken’s research was called Defense Independent Pitching Theory (DIPs Theory). It’s the building block of much of today’s pitching analysis. It can be a tricky concept to understand and counter-intuitive for most baseball fans. Refer to our sections on DIPs, BABIP, and Luck for more information.
● FIP does a better job of predicting the future than measuring the present, as there can be a lot of fluctuation in small samples. It is less effective in describing a pitcher’s single game performance and is more appropriate in a season’s worth of innings.
Links for Further Reading: