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Rick Lucks breaks down how to use BABIP to identify potential pitching sleepers and busts as his series on making sabermetrics more accessible to fantasy baseball managers continues.
While FIP is a useful tool to predict a pitcher's future ERA performance, fantasy managers should remember that ERA, not FIP, is what matters in most formats. This means that we are interested in the "luck" that separates the two statistics.
While some of this luck is unpredictable, we can and should predict some of what goes into a pitcher's bottom line. BABIP plays a big role in the variation of a pitcher's perceived luck, but it may not be as clear-cut as it seems.
A pitcher's BABIP appears on the first graph of their player page on FanGraphs, so it's easy to locate. Let's get to it!
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How to Interpret BABIP for Pitchers
When calculating BABIP for hitters, we assume a neutral defense because they figure to see a balance of poor and skilled defenders as they travel around the league. This is not true for pitchers, as they always pitch in front of their own club's defenders. A team with Jonathan Schoop's 27 Outs Above Average in 2022 figures to provide better defense to its pitchers than a team that lacks a premium fielder, helping pitchers sustainably outperform their FIP.
Outs Above Average (OAA) is a Statcast metric that makes it easier to look at the quality of a team's defense. OAA measures each player's defensive contributions using Catch Probability. If a batted ball is caught by a player, the player receives OAA credit equal to 1 – the ball's Catch Probability. For example, a successful catch on a ball with a 40% Catch Probability is worth 0.6 OAA (1 - 0.4 = 0.6).
Players also lose points equal to the batted ball's Catch Probability if they flub the catch. Missing the ball in the example above would subtract 0.4 from the player's OAA. One of the best features of OAA is that you can sort the leaderboard by team and even the pitcher on the mound, removing the guesswork from the equation.
For example, Cal Quantrill of the Cleveland Guardians led all pitchers in defensive support received with 15 OAA behind him. Cleveland ranked fifth in baseball with 21 OAA as a team last year, so Quantrill will probably receive above-average defensive support again in 2023. However, he probably won't receive the same level of defensive support he did last year. You may not want to bet on a repeat of last season's 3.38 ERA as a result.
Lopez led all infielders in OAA last season, while Daulton Varsho took the top spot among outfielders with 18. There are other defensive metrics, but they are much more abstract than OAA while also leaving out important pieces of the puzzle. Ultimate Zone Rating (or UZR) makes no effort to account for shifting, rendering it completely obsolete in this author's estimation. Defensive Runs Saved (DRS) has one fantasy purpose: measuring the value of a pitcher's defensive contributions to his own cause.
For example, Tyler Anderson led pitchers in DRS in 2022 with five over 178.2 IP. Anderson has always been an outstanding defensive pitcher, but spending most of his career at Coors Field prevents it from showing up in his career stats. Anderson should be expected to support himself with his glove again in 2023, making his .256 BABIP allowed last season look more sustainable. That's what the Angels are hoping for!
What Else Impacts a Pitcher's ERA?
BABIP is also partially determined by a pitcher's style. An extreme ground ball pitcher may have a higher BABIP against because grounders have higher BABIPs than fly balls (.235 to .118 in 2022.) This stylistic difference also changes how much a given pitcher will benefit from (or be hindered by) a particular defender on his team. For instance, a ground ball specialist would love to pitch in front of Schoop while a fly ball guy would benefit more from an elite outfielder like Varsho instead.
While the defense is largely out of a pitcher's control, some pitchers can control their BABIP to a degree. For example, you would probably be tempted to say that the .240 BABIP Justin Verlander allowed in 2022 was a fluke, and you would be partially right. However, Verlander combined a strong fly ball tendency (43.6 FB%) with an above-average IFFB% (19.7%). The combination would be expected to produce a low BABIP allowed.
Every pitcher allows a few hits, and the sequencing of these events may also cause a difference between a pitcher's FIP and ERA. Allowing three base hits over three innings is probably harmless while allowing three hits in one inning and then nothing in the next two frames likely puts a run on the board.
Sequencing luck is measured by strand rate or LOB%, and research shows that it is largely an unstable, luck-driven stat. In 2022, the league average LOB% was 72.6%, with higher numbers generally forecasting a higher ERA moving forward. Elite strikeout guys tend to be the best at getting the K "when they need it," and as such may sustain slightly elevated strand rates.
Conclusion
To conclude, a pitcher's BABIP includes some unknown variables but also some predictable inputs. The quality of his defense can help or hurt him. Sequencing does not affect BABIP but can impact a pitcher's ERA substantially. A given pitcher's style, as a ground ball or fly ball specialist, may also impact his performance. If you would like to learn about other advanced stats, stay tuned to our series.
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