Leading up to opening day we will be running an advanced metric primer series. The goal of the series is to introduce readers to advanced baseball metrics in a fun and Orioles-centric context. Today’s entry is on Fielding Independent Pitching (FIP) and it represents the first entry in the series. If you do not have time to read this whole article please at least watch the youtube video on FIP in this post. Much like Joseph ‘Blue’ Pulaski, it is glorious.
FIP is a measure of the outcomes a pitcher is directly responsible for: homeruns (HR), walks (BB) and strikeouts (K). FIP applies weights to each of these outcomes to generate a number that looks like Earned Run Average (ERA). However, FIP and ERA can greatly differ. The development of FIP came from Voros McCracken’s discovery that, “there is little if any difference among major-league pitchers in their ability to prevent hits on balls hit in the field of play.” As a result a metric describing a pitcher’s ability should not include the effects of balls hit in the field in play. Instead a metric should only reflect those things a pitcher can control – a pitcher’s skills – HRs, BBs, and Ks. The exact formula for FIP is: ((13*HR)+((3*BB)-(2*K))/IP) + constant. The constant is usually around 3.2.
The difference between most of the traditional baseball metrics and the advanced baseball metrics is that the traditional metrics measure what happened and advanced metrics measure a player’s contribution to what happened. In this case, ERA measures how many runs the other team scored while the pitcher was on the mound . While FIP measures the pitcher’s ability to prevent those runs scored, independent of the ability of the pitcher’s teammates. This difference makes FIP better at predicting a pitcher’s future performance than ERA.
An example helps illustrate FIP’s superior predictive ability. Here, we’ll look at former Orioles closer George Sherrill. During his 2009 season, in which he posted a 1.70 ERA, Sherrill was dealt from Baltimore to Los Angeles. In Los Angeles in 2010, Sherill posted a horrendous 6.69 ERA. While Sherrill’s ERA rose ~5.00 runs in from 2009 to 2010, his FIP rose less than 2.00 runs. Furthermore, Sherrill’s FIP has been more stable throughout his career than his ERA. While this is only one example of FIP’s superior predictive abilities it represents a trend that exists over different pitchers and many seasons.
One way to use FIP is to validate a pitcher’s ERA. If a pitcher has both a low ERA and a similarly low FIP it likely that the pitcher’s ERA will continue to remain low. We can draw this conclusion because the runs the pitcher has prevented are mostly due to his skills than the skills of his teammates. However, if a pitcher has a low ERA, like Sherrill’s 1.70 ERA in 2009, with a significantly higher FIP, like Sherrill’s 3.21 in 2009, we can expect his ERA to rise. This conclusion stems from the observation that the pitcher’s ability to limit runs is less a product of his skills and more a product of his teammates’ skills.
Now without any further ado I present to you the single greatest piece of FIP-centric media ever created. If comes courtesy of our AL East brethren at DRaysBay.com.