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The league average batted ball distribution in 2018 was 21.5% liners, 43.2% grounders and 35.4% flies. We have previously seen how pitchers may specialize in either grounders or fly balls.
Fly ball pitchers have a BABIP advantage over their ground ball-inducing counterparts, since fly balls (.117 BABIP in 2018) consistently have lower BABIPs than worm killers (.236). Yet most fantasy owners prefer to roster ground ball pitchers to the point that GB% is frequently cited as a peripheral stat to determine fantasy viability. Why is this the case?
Let's get to it!
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How to Interpret Pitcher Batted Ball Distribution
The reason is slugging percentage. Fly balls had a collective .690 slugging percentage in 2018 despite the lower BABIP, while grounders had just a .258 SLG. As Khris Davis hits more home runs than most in part by elevating the ball more frequently, fly ball pitchers are liable to give more up by allowing more airborne baseballs. Fantasy owners can live with the odd single through the infield if it means fewer homers allowed.
This line of thinking makes intuitive sense, but I feel it may be overstated at times. Good fly ball pitchers tend to post HR/FB rates a little better than the league average, somewhat limiting the long balls they allow. A pitcher's home park may also help suppress home runs allowed. Once dingers are under control, a fly ball pitcher actually offers several advantages over a ground ball specialist.
For example, fantasy owners may reap the benefits of a lower WHIP by investing in a pitcher that makes his living in the air. If the ball leaves the yard, a fly ball pitcher also has a greater probability of it being a solo shot instead of having to watch a crooked number go up on the scoreboard.
Last season, Washington's Max Scherzer was an excellent example of an effective fly ball fantasy pitcher. He posted a 2.53 ERA and 0.91 WHIP thanks in part to a .265 BABIP that seems way too low to sustain. Yet his 47.6% FB% predisposed him to limiting BABIP, and he induced pop-ups at an above average rate (16.1% IFFB% last year). His 9.7% HR/FB was significantly lower than the league's mark (12.7%). Obviously, Scherzer's fly ball game is very effective.
To be clear, pitchers in homer-happy locations such as Milwaukee's Miller Park, Yankee Stadium, and Guaranteed Rate Field in Chicago should absolutely be ground ball guys if they are rostered in fantasy. It is also a useful metric to look at when trying to determine if a given pitcher should be active for a road start at these locations. Still, a high GB% alone should not make a guy fantasy relevant.
A specialty in either grounders or flies may allow a pitcher to maximize the team behind him and beat FIP. For example, we already saw how a guy like Lorenzo Cain can use his defensive prowess to help his team's pitchers suppress BABIP. Josh Hader had a 48.4% FB% in his magical 2018, giving Cain plenty of defensive opportunities that may have helped the pitcher post a microscopic .220 BABIP.
It should be noted that there are some limitations with this kind of analysis. Much like offensive support, defensive support can vary from pitcher to pitcher even if they have the same players behind them. It is a useful piece of the puzzle, but should never be the only thing you look at.
Research also indicates that extreme pitchers gain a small platoon advantage against like bats, so GB pitcher vs. GB hitter favors the pitcher. The effect isn't quite as large as the more traditional handedness platoon split, and is tough to use in weekly formats or daily leagues that cap transactions. Still, it can be useful for DFS and may be cited as a reason to avoid pitchers with an average batted ball distribution.
Conclusion
Both ground ball and fly ball specialists have their uses in fantasy. Ground ball specialists offer lower slugging percentages against and can take full advantage of an elite defensive infield. Fly ball specialists offer superior WHIP and make the best use of an elite defensive outfield. Both gain a minor platoon advantage against hitters that share their specialization, an advantage never enjoyed by arms with no particular tendency. Next time, we'll look at a tool that can forecast and confirm spikes in everything from GB% to K%: Pitch Info.
