Modern baseball statistics revisited

Last year I wrote a series of articles explaining some of the modern statistics that baseball announcers currently use in broadcasts. The series focused on all of the components that produce the statistic Wins Above Replacement (WAR). Those statistics, however, were just focused on batters. Pitchers also have their own version of WAR. In this series I’ll break down the individual components of a pitcher’s WAR starting with Fielding Independent Pitching (FIP).

FIP is now referenced more often in broadcasts than earned run average (ERA). As the name suggests, FIP attempts to neutralize the effects of fielding so a pitcher is not rewarded or penalized based on his team’s defense. ERA is subject to judgement calls by official scorers to determine what is or is not an earned run. It also does not take into consideration the skill level or fielding range of a defender. For example, compare a twenty-six-year old Omar Vizquel to the thirty-nine-year old version. Both were Gold Glove winners and played similar number of innings per game, but the younger version was able to make almost one extra play on defense each game. All those plays the older Vizquel couldn’t get to are not considered errors which would result in a higher ERA for the pitcher.

FIP attempts to neutralize this by measuring what plays were in a pitcher’s direct control. This includes strikeouts, walks, hit batters and home runs allowed. Here is the formula that FanGraphs uses.

FIP = [(13xHR) + (3x(BB+HBP)) – (2xK)] / IP + constant

Key: HR = home runs allowed, BB = walks, HBP = hit by pitch, K = strikeouts, IP =innings pitched, constant = value calculated each year to give FIP a similar scale to ERA. This value can be found online at either baseball-reference.com or fangraphs.com. A value of 3.10 can be used as a good estimate.

FIP is a good statistic to compare pitchers within the same season. It’s also good for pitchers who played in the same era. Since home runs are such an important part of the formula the league average FIP can vary widely from season to season. Below are two tables the first has a list of familiar Mariner pitchers, their FIP, ERA and the league average FIP for that year. The second table is from FanGraphs and gives you a general idea of a pitcher’s season had based on his FIP.

Table 1.

Player Year FIP ERA League Average FIP

Randy Johnson 1995 2.08 2.48 4.45

Jamie Moyer 2001 4.17 3.43 4.42

Felix Hernandez 2010 2.27 3.04 4.08

Taijuan Walker 2016 4.22 4.99 4.19

Yusei Kikuchi 2019 5.46 5.71 4.51

Table 2.

FIP Rating

3.20 Excellent

3.50 Great

3.80 Above Average

4.20 Average

4.40 Below Average

4.70 Poor

5.00 Awful

When a pitcher’s FIP is significantly lower than his ERA, this usually means the pitcher has given up a high average of balls in play. This can be an indication of how the defense is playing behind the pitcher. Looking at the first table we see Randy Johnson’s FIP was forty points below his ERA in 1995. That year the starting shortstop and third baseman were 30-year-olds, Luis Sojo and Mike Blowers. The Mariners in general, with the exception of Ken Griffey Jr. in center field, were made up of older players not known for their great defense.

When a pitcher’s FIP is significantly higher than his ERA, it can mean that the pitcher doesn’t have a high strikeout rate. Jamie Moyer is a good example of this. His FIP was higher than his ERA most every year of his career. Moyer’s success over his 25-year career was built on control and creating weak contact. Pitchers like Moyer will be outliers for FIP. The other explanation can be that the pitcher has a very good defensive team behind him.

A parting note on FIP. It is not park factor neutral. Pitchers in hitter friendly parks tend to have higher FIPs. As we will later see in future articles this is adjusted for when determining a pitchers WAR.