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The most accessible of the fantasy-relevant advanced stats is BABIP, or Batting Average on Balls In Play. It simply measures a player's batting average on balls in play, with outcomes such as strikeouts and home runs removed from consideration. In general, the league average hovers around .300, a nice round number to remember. However, it has been trending downward in recent years with 2022's figure coming in at .290 league-wide.
Many know BABIP as an approximation of luck, with either a very high or very low number indicative of a major batting average regression in the future. That is partially correct--the stat can be used to predict batting average fluctuations. However, a player's skills may allow him to consistently run a better-than-average BABIP, or doom him to a consistently below-average figure.
There are two primary sources to look up a player's BABIP: FanGraphs and Baseball-Reference. They don't always have the same figures, and FanGraphs tends to be preferred because the site lets you look at BABIP by batted ball type (more on that below). Just type in a player's name in the search bar provided and his BABIP is displayed in the first chart that pops up. Now that you know where to find BABIP, let's explore how to use it.
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The Above-Average BABIP Formula
If you want an example of a batter who sustainably runs high BABIPs, look no further than the newest Philadelphia Phillie Trea Turner. Turner hit .298/.343/.466 in 27 SB thanks in part to a .342 BABIP more than 50 points better than the league average last season. If we regressed his BABIP to .290, Turner would not only help fantasy managers less with his average but have fewer opportunities to steal a bag. The Phils likely would have also wasted $300 million.
Fortunately for Turner, much of his BABIP boils down to sustainable skills and not dumb luck. His career BABIP is .344, two points higher than what he did last year. As the 27 SB might suggest, Turner can fly. He can turn groundouts for other players into singles, giving him a consistent source of base hits to prop up his BABIP, batting average, and overall fantasy value. Of course, running really fast doesn't mean that Turner couldn't be fortunate or unfortunate in any given season. How can fantasy managers tell the difference?
Looking at BABIP by batted ball type can be a great tool for examining this. Turner gets his speedster hits exclusively on grounders, as running fast does nothing to prevent a fielder from catching an airborne ball. While the league averaged a .234 BABIP on grounders in 2022, Turner posted a .319 mark on them. His career rate is even better at .329. Therefore, we can conclude that Turner should continue to dramatically overperform the league average BABIP on ground balls in 2023 and beyond.
Comparing BABIPs for the other batted-ball types is something of a mixed bag for Turner. His fly balls found pay dirt less frequently last season, posting a BABIP of .114 against a career mark of .123. However, his line drives fared considerably better (.726 BABIP last year) than they have historically (.690 career). Overall, both figures should be expected to regress, meaning Turner's BABIP will drop slightly as he'll lose more base hits on liners than he gains on flies. We should probably expect Turner to fall just shy of last season's BABIP.
BABIP takes multiple seasons to stabilize (or become predictive), and you need to avoid rushing to conclusions when using it. A rookie who posts a .380 BABIP should not be expected to keep it up because that's suddenly his baseline. That said, an established player's baseline is more predictive of future performance than the league average barring other factors changing.
The Below-Average BABIP Formula
The same trend is possible in a negative way. For example, fantasy managers know Joey Gallo as a potential power source who will drain your roster's batting average thanks in large part to a consistently low BABIP. Last season, Gallo posted a BABIP of just .219 and a batting average of .160, creating batting average upside if you think it will regress to .290. Unfortunately for Gallo, that isn't happening.
While Turner's speed grants him extra base hits, Gallo's average speed means that he is retired on grounders that Turner can beat out. He also hit just 9.6% of his ground balls to the opposite field, allowing opposing defenders to cheat to one side with an infield shift every time up. The result was a .173 BABIP on grounders that was only slightly lower than his .187 career mark.
That's not the end of Gallo's BABIP problems though. He also hits an above-average number of pop-ups with a 13.3 infield fly ball (or IFFB%) rate last season. Pop-ups are nearly always caught with minimal difficulty, so players who hit a ton of them tend to run low BABIPs. Sure enough, Gallo's career BABIP on flies of .084 looks great compared to the .038 he put up last season. It's easy to see why Gallo struggles to post even a league-average BABIP season after season. That won't change in 2023.
Conclusion
To conclude, BABIP can be used to indirectly measure a player's batting average luck by comparing it not to the league average but to an established player's career number. Younger players without an established baseline are generally regressed to the league average, but these predictions are less reliable than those based on a player's personal history.
Foot speed, batted ball authority, line drive rate, and defensive positioning all give players some ability to manipulate BABIP. Players with these skills may still overachieve, and this regression can be predicted by examining BABIP by batted ball type. Our next installment will look at HR/FB and why it is sometimes called the BABIP of power.
