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Fly balls can turn into home runs. Ground balls never do. It would seem as though fantasy owners want their batters to hit nothing but flies, yet this is not always the case.
Why would this be? The answer, of course, comes down to batted ball distribution and how batters make contact. The league average batted ball distribution in 2019 was 21.4% line drives, 42.9% ground balls, and 35.7% fly balls. The 2020 season saw virtually identical numbers: 21.6 LD%, 42.7 GB%, and 35.7 FB%. Most individual players vary from this standard breakdown, providing insight into their fantasy viability.
In this article, we'll continue evaluating the most effective ways to use sabermetrics to get an edge in your fantasy baseball leagues. Examples will be drawn primarily from 2019 for more reliable sample sizes.
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The Value of Line Drives
Let's first look at how all major leaguers fared on each of the major types of a batted ball in 2019. Grounders generated a BABIP of .236. Flies were not as productive, posting a .118 figure. This makes sense, as pop-ups seldom fall in, cans of corns to the outfield are only slightly better, and homers are considered out of play and do not count toward BABIP. Line drives turned into base hits far more frequently than either of the others, posting a .678 BABIP. The difference between liners and anything else is startling. Batters want line drives.
Tim Anderson's stellar 2019 provides a good illustration of what a few extra liners can do. He posted a .335/.357/.508 triple-slash line thanks in part to a 23.8% line drive rate, a far cry from his career line of .276/.303/.475. Anderson was an afterthought in real and fantasy baseball terms heading into 2019 but ended up surprisingly productive in both areas.
A player's LD% tends to bounce around the league average with random spikes and drops, none of which offer much predictive value moving forward. Anderson has a 20.7 LD% over his career, so luck was almost certainly the primary driver of his 2019. Sure enough, Anderson's LD% fell to 18.9% in 2020's shortened season. When BABIP is driven by luck, LD% is usually why.
This is not to suggest that no one consistently posts above-average LD% rates. For example, Joey Votto's career .345 BABIP is driven by his career 25.6 LD%. Considering the length of his career, it would be stupid to suggest that Votto has enjoyed a lucky decade-plus. Therefore, we give credit to Votto for being a plus-BABIP guy due to a LD% skill, just like we give Christian Yelich BABIP credit for his blinding speed. This distinction has to be earned over numerous full seasons, however. Most LD% surges are more fluky Tim Anderson than sustainable Joey Votto.
Which Is Better: Ground Balls or Fly Balls?
Unlike LD%, both GB% and FB% are stickier--a player with an elevated rate in one is likely to repeat a similar rate moving forward. By BABIP alone, grounders are better. However, this changes significantly if slugging percentage is considered. In 2019, grounders offered a slugging percentage of .258, only slightly higher than the .236 BABIP they posted. Flies had a .788 slugging percentage, easily offsetting the lower BABIP for most fantasy players. Sluggers like Cody Bellinger who lift the ball at an exceptional rate have a built-in slugging advantage because of their batted ball profiles.
The ideal batted ball mix, therefore, varies with the player. Elite speedsters want more grounders than flies as they don't have the oomph to hit a lot of homers anyway. One-dimensional sluggers want fly balls, especially since the shift and a lack of speed prevent them from realizing the larger BABIPs associated with grounders anyway. Fantasy owners usually prefer players with power and speed potential to have a higher FB%, as the extra power is more beneficial than a few extra times on base.
Incidentally, line drives averaged a ridiculous .916 slugging percentage to go with their .678 BABIP in 2019, so they are still the batted ball of choice.
Conclusion
To conclude, line drives are by far the most productive result for hitters. BABIP's luck-driven fluctuations are frequently driven by LD%, a largely random stat. GB% and FB% are more predictive, and which one is favored depends on the hitter in question. Grounders offer a higher BABIP, but almost zero power. Flies result in base hits less often, but generate much more power when they do.
The intricacies of BABIP could be a never-ending topic, but the information provided so far is generally enough for fantasy purposes. Check this out to learn about some other metrics that can help you predict a player's performance.
