This week I’m keeping with the baseball theme and taking a look at the FIP Leaders in the Frontier League.
When I was younger, I’d crack open the Chicago Tribune Sports section and go immediately to the baseball section. After reading the relevant articles about the most recent Cubs loss, I’d scan down to see the league leaders in the pitching and hitting categories. The leaders in the pitching category were typically sorted by strikeouts and earned run average (ERA). ERA, calculated as the number of earned runs a pitcher gives up over 9 innings, used to be the gold standard of pitching evaluation. It’s obvious that if a pitcher gives up few runs then a team will likely win more games.
However, ERA doesn’t tell the whole story. What if a pitcher’s defense is awful? The pitcher doesn’t have control over what happens in the field once the ball is put in play, so if the defense behind the pitcher is subpar, then it’s likely the pitcher will have a higher ERA. Fielding Independent Pitching (FIP) was created to evaluate pitchers in a different way.
FIP measures exactly what it means — fielding independent pitching. FIP measures only things that pitchers can control: strikeouts, walks, batters hit, home runs allowed, and innings pitched. League ERA is included to bring FIP onto the ERA scale, as well.
Here’s the formula for FIP from Fangraphs:
Now we need to find the FIP Constant, which isn’t that difficult. Here’s the formula:
FIP Constant = lgERA — (((13*lgHR)+(3*(lgBB+lgHBP))-(2*lgK))/lgIP)
Using Baseball Reference information for the Frontier League, I created a database of every pitcher who threw innings during the 2020–2021 season. Using the above formula, I found that the FIP constant for the 2021 Frontier League is: 3.658997. Now we can use the FIP Constant to find out who were the Frontier League Leaders in FIP for the 2021 season. There were more than 350 pitchers who threw at least 1/3 of an inning during the season, so I’m only going to focus on the pitchers who threw the most innings.
Here’s the pitchers with 100+ innings during the season:
The top pitchers have some decent FIPs that match well with their W-L record. Tim Holdgrafer’s FIP is below his ERA, although not by much, indicating that he had a little bad luck during the season. Ryan Hennen’s FIP, while still very good, is significantly higher than his ERA. Both Ryan Middendorf and Polo Portela have high FIPs but have a solid W-L record. Portela has a high FIP because he walked 36 batters, the third most in the table and gave up 14 home-runs, second most. Middendorf gave up 15 home-runs and walked 23. Both those pitchers, however, have the ability to give up fewer runs than their FIP suggests.
FIP is by no means perfect. It’s a good starting place for pitcher performance analysis, and over the course of multiple seasons a pitcher’s FIP and ERA should track together pretty closely. A lot of different things can happen in a baseball season, however. Pitchers who can generate a lot of fly balls or limit stolen bases will likely beat their FIP since there’s less luck and variation involved in those events than ground balls or line drives.
For now, we have baseline FIPs for the 2021 season. It’ll be interesting to see how these numbers hold up in the spring once the 2022 season gets underway.
https://github.com/firstpitchstrike/Baseball_Analytics/tree/main
https://library.fangraphs.com/pitching/fip/
https://www.baseball-reference.com/register/league.cgi?id=d70cbe6d
