The Importance of FIP: An Analysis

Dave Stieb pitching off the mound; CC by 2.0 License

One of the most common knocks on sabermetrics is how certain stats are flawed. I am not going to talk about how FIP is a perfect stat and is the end-all, be-all when it comes to advanced stats. FIP is a very flawed stat with holes. However, it is also a highly important metric in the world of baseball today and needs to be understood for all levels of baseball players. So, first of all, what is FIP?

FIP is a stat that is based on the work of Voros McCracken on defense-independent pitching statistics. Tom Tango and Clay Dreslough made the stat itself and they first called it “Defense-Independent Component ERA.” The stat has gained some popularity as of late due to the ease with which it is calculated. Unlike some other advanced stats such as SIERA and wOBA, FIP is much easier to calculate as it requires easy-to-remember constants paired with basic math.

13xHR+3x(BB+HBP) - 2xK

FIP= ----------------------------- + FIP constant

IP

The FIP constant is used to bring FIP onto the same scale as ERA. There is a formula for the FIP constant; however, if looking at the MLB, it is roughly 3.1-3.2. It all depends on the run environment of the league in which you are playing. If you are coaching/playing in high school and the average ERA is over 5, then the FIP constant would adjust to around a 3.4-3.5 range. It all depends on the league average ERA of whichever league one is in. The FIP constant equation is listed below:

lg=League (13xlgHR)+(3x(lgBB+lgHBP))-(2xlgK)

FIP constant= lgERA minus -------------------------------------

League IP

Now, what does FIP mean? FIP stands for Fielding Independent Pitching. It takes a pitcher's numbers and completely neutralizes any ball that is put in play. It only looks at the outcomes that a pitcher has 100% control of, those being Strikeouts, Walks/HBP, and Homeruns. It is often used to show the “luck” of a pitcher because if a pitcher has low FIP, that means they are striking out batters and not giving up walks or home runs. However, if that same pitcher has a high ERA, he are seen as unlucky because his FIP is low.

How to Use FIP

FIP is a stat to be used with other stats. One cannot just look at it to determine a player's value. FIP tells a story of how good a pitcher is compared to his ERA, as displayed below.

If we look just at the ERA of these guys, then Kluber was awful, while Greene was mediocre and Quantrill very solid. However, looking at the FIP would make someone think they are all similar pitchers. Neither of these statements are incorrect because it is important to look at BOTH ERA and FIP. Here is how one would evaluate these pitchers by looking at just the numbers above.

Hunter Greene

Greene underperformed his FIP slightly, as his 4.21 ERA is higher than his FIP. This indicates that he likely was very good at 1 of 3 components of FIP while not being as good at the other 2. This would depict value in keeping Greene around, and if he can pitch his way to a more well-rounded FIP, he has a high ceiling.

Cal Quantrill

Quantrill is in the opposite spot as Greene. His ERA was lower than his FIP, meaning he overperformed his FIP. Looking at this makes me think that he allowed a lot of balls in play with weak contact. His K/9 was likely below average and HR/9 and BB/9 above average, which would lead to more balls in play. I do not expect much progression from Quantrill, but regression isn't likely either. He is be a safe bet for any rotation this year.

Corey Kluber

Kluber’s season is a very interesting case study, as his ERA was higher than one would expect by looking at his FIP. Looking at those numbers makes me think that Kluber was hit very hard while also keeping his walks low and K/9 high. This would give me some hope for Kluber going into next year, especially if he can start to avoid hard-hit balls. However, I would be very cautious with him. If his BB/9 gets even a little worse, he could completely implode.

It is highly important to understand how to use FIP and when to use it. It is a very valuable stat that can show a lot from a pitcher. As mentioned above, much can be evaluated by just looking at the FIP and ERA of a pitcher. However, some serious issues with FIP itself still need to be understood.

The Bad Side of FIP

I cannot talk about FIP without talking about the clear flaws in the stat itself. FIP avoids all batted balls, which is a good thing in the sense that it can simplify a pitcher into the 3 true outcomes. However, it can tend to oversimplify a pitcher in the way it did with Kluber. Taking a look at Kluber’s baseball savant page, he was not good this year. But he was very good at limiting walks, which made his FIP seem a lot better than he was. This tends to happen when a pitcher has one ELITE component of FIP but is average or poor in the other components. It can easily lead to a FIP that is lower than the pitcher's performance would indicate. In conclusion, take FIP with a grain of salt and use the other stats around to help evaluate the player.

Another big issue with FIP is that it tends to favor power pitchers. These are guys with absurdly high K/9 and sometimes good BB/9 or HR/9. Look at Hunter Greene, for example. He is a power pitcher in the making, with a high 90s fastball and a lot of strikeouts to his name. This led to his lower FIP than expected. On the flip slide of this, FIP can also hurt contact-based pitchers that do not rely on strikeouts. An example of this comes from the great Greg Maddux compared to Nolan Ryan.

Nolan Ryan and Greg Maddux during 4-year peak

As most know, Maddux was known for being a very contact-based pitcher who relies, which leads to a low K/9 rate. Ryan was very much a power pitcher who liked to rely on strikeouts. Looking at the stats above, it is clear that Maddux had a 4-year peak that Nolan Ryan could not touch. However, despite their ERA being over a one-run difference, their FIP is in the same ballpark. One would think that Maddux should have a far better FIP based on his dominance in other stats, yet Maddux being a contact pitcher comes back to hurt him in terms of FIP. Greg Maddux's K/9 was only 7.0, compared to Nolan Ryan's K/9 of almost 10. This is a prime example of FIP favoring power pitchers way more than contact pitchers.

Another main issue with FIP is that it completely discounts balls in play, implying that pitchers cannot control them. An example of how stupid this can be is found by comparing Oneil Cruz and Tony Kemp. In the 2022 season, Oneil Cruz hit a 122.4 MPH exit velo single. This was the hardest-hit ball in the 2022 season, yet it did not hurt the pitcher because it was just a single. On the flip side, Tony Kemp hit a home run with an exit velo of just 95 MPH. Only one of these two pitches went back to hurt the pitcher's FIP, and it was not the HARDEST hit ball of the 2022 season. Instead, it was just the 95 mph HR.

The Importance of FIP

With all that being said, FIP is still a very important stat. It can be an easy stat for all players and coaches to evaluate performance. FIP can help show how valuable a pitcher is at the most important parts of pitching. As said above, it should never be used by itself when evaluating stats. One way to adjust FIP for younger levels of sports is to adjust the HR stat. In lower levels of baseball, HRs are not common and do not have as big of an impact as they do in the majors. Instead of using HRs, one could use XBH to gauge the impact of getting hit hard. FIP can also be important when coaching players. It can be easy to see if a pitcher has been as bad as he seems, and it can be used to see how a player can get better. For example, if a kid had a 5.43 ERA but a 4.23 FIP, then there is some hope for that kid, as he is doing better than his ERA shows. FIP is also gaining a lot more importance today with the increase in “3 true outcomes,” which are walks, HRs, and strikeouts. With the rise of "3 true outcomes" players, the main components of FIP are more prevalent, making FIP a lot more useful.

To show the importance of FIP and how it can be used, look back at the 1982 AL CY Young race before FIP was an important stat.

Looking at these numbers, it is clear to me that Dave Stieb should have won the Cy Young, but the voters in the 1980s looked mostly at ERA and W-L record, so they gave the award to Vuckoich. One might think that this does not matter, but Stieb was a guy who got robbed of 1-2 Cy Young awards, which is a big reason why he is not in the HOF. If FIP was a stat back then, it can be reasonably assumed that Steib could have had a much better chance to win a Cy Young award or two, which could have landed him in the HOF.

The importance of FIP cannot be understated. It helps to provide a different lens to look at pitchers, which can change the whole perspective surrounding them. It is by no means a perfect stat, but it helps show the whole picture when evaluating players.

Conclusion

FIP is an important but misunderstood and misused stat. FIP needs to be used across all levels of sports. However, it needs to be used in the correct way and used with other stats to show its value. By no means is FIP a perfect stat. However, with the simplicity of the stat and the value it can show alongside ERA, it is quite valuable. I encourage you, if you're a fan, coach, player, or some other involved with baseball, to learn about FIP as it can help a lot with all aspects of baseball.

Sources

- FanGraphs

- Baseball reference