Using Sabermetrics for Fantasy Baseball: Pull%

March 6, 2021

Rick Lucks breaks down how to use Pull% to project and validate a hitter's power as his series on making sabermetrics more accessible to fantasy managers continues.

We have previously determined that fantasy managers generally prefer batters to hit the ball into the air to have a chance at a home run. Yet, all fly balls are not equal for this purpose. A player can maximize his power production by pulling the ball in the air.

One way to illustrate this is to look at league-wide HR/FB by batted ball direction. Flies to the opposite field seldom found the cheap seats in 2019, posting a HR/FB of just 6.1%. Flies to dead center fared slightly better (10.8% HR/FB), but pulled fly balls were clearly the most productive (37.1% HR/FB). The exact numbers vary slightly, but every season illustrates this trend.

Let's take a closer look at how Pull% can help you win your fantasy leagues in 2021!

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How to Interpret Pull%

In 2019, roughly 58% of all home runs were to the batter's pull side. Only 16% of homers went to the opposite field, with the remaining 26% going out to center. This distribution is fairly consistent year-to-year, so it's safe to count on something similar going forward.

In a way, this makes intuitive sense. Pulled baseballs tend to be hit with the highest exit velocity, making it easier for them to leave the stadium. The power alleys next to the foul poles on either side of the ballpark also present the shortest distance to the cheap seats. If a player's HR/FB dramatically improves, a change in approach involving more pulled baseballs could help explain why.

How Pull% Affects Fantasy Performance

Boston's Xander Bogaerts provides a good illustration of this kind of change. In 2015, he pulled only 16.7% of his fly balls, producing a HR/FB of 5.3% and a total of seven dingers. He significantly upped his power game in 2016 by pulling 28.1% of his flies, leading to a much higher 11.4% HR/FB and 21 bombs on the campaign. The increased power was not exclusively the result of the Pull% spike, as he upped his FB% as well (25.8% in 2015, 34.9% in 2016). It helped to validate his HR/FB increase, though.

His change in approach did not last. Bogaerts pulled only 24.5% of his flies in 2017, dropping his HR/FB to 7.2% and his season HR total to 10 in the process. Once again, the raw number of fly balls Bogaerts hit decreased (30.5% FB%), so the change in Pull% was not solely responsible for the loss of power. This example illustrates that while a change in Pull% can support an increased HR/FB, it may not reflect a permanent change.

In 2018, Bogaerts clubbed 23 HR on the back of a FB% spike (35.6% FB%) and a 15.5% HR/FB. However, his Pull% on fly balls decreased to 23.7% that season. Bogaerts finally put it all together in 2019, posting a career-best 33 long balls on the back of a career-best FB% (39.8%) and a 29.3 Pull% on those fly balls that contributed to a 16.7% HR/FB. The shortened 2020 season saw Bogaerts club 11 homers with a 36.2 FB% and 18.6% HR/FB, though his 20.3 Pull% on flies fell short of the previous year's standard.

The Problem with Raw Pull%

Of all pulled baseballs in 2019, 58.2% were grounders. Pulled grounders might have a higher average exit velocity than other ground balls, but the shift still eats them up with minimal difficulty. They will never turn into home runs. In contrast, only 21% of pulled baseballs were classified as fly balls last season. Ideally, fantasy owners want their hitters to pull fly balls while limiting how often they roll grounders to their pull side.

This is much easier said than done, as all players pull many more grounders than flies. Let's consider Mike Trout as an example. His raw 2019 Pull% of 42.4 was marginally higher than the league average 40.7%, and he pulled 61.6% of his grounders compared to 28.7% of his flies. At first glance, you might think that Trout was making himself vulnerable to the shift without significantly boosting his power potential.

That assumption would be wrong. The shift was designed for batters who pull much more than 61.6% of their ground balls, allowing Trout to hit a solid .303 against it that year. Many batters fail to pull even 20 percent of their flies, so Trout rated well enough in that regard as well. Pulling more grounders than flies is far from a death sentence.

Conclusion

To sum up, pulled fly balls tend to perform better than other fly balls. This means that pulling more flies can produce an increased HR/FB, but you should never use raw Pull% to determine this. Most pulled balls are hit on the ground, where all of the exit velocity in the world cannot turn them into home runs.

Therefore, you should filter a player's Pull% by batted ball type to produce the most reliable results. If you're interested in learning more about the role of advanced analytics in today's fantasy environment, check out some of our other articles on the subject!

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