David Fletcher Has Refined His Ground Balls

Written by: Justin Choi (@justinochoi)

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On September 21st against the Texas Rangers, David Fletcher put 5 balls into play. He singled twice, lined out twice, and reached on a fielder’s choice. None carried an exit velocity above 100 mph. One line out did have a launch angle of 33 degrees – a rare feat for Fletcher – but traveled at a mere 58.6 mph, losing strength as it entered the glove of shortstop Anderson Tejeda. 

It was a typical day for David Fletcher, who despite his poor batted ball data thrives on his high contact rates. He’s also picky about when he swings, allowing him to whiff less and draw walks at a rate that leaves his slap-hitting peers (e.g. Hanser Alberto) in the dust. Good hitters boast qualities that distinguish themselves from the rest. For Fletcher, that quality is an optimization of both patience and aggression. 

It’s a trait he’s consistently exhibited for many years. But in 2020, Fletcher seems to have refined a new, emerging skill of his: the ability to hit ground balls. 

Contrary to popular belief, Fletcher was never an archetypal ground ball hitter. He ran a 39.4% ground ball rate in his 2018 debut season, which ranked 185th of 278 players with at least 300 PAs. A player who tied him? Joc Pederson, who’s the antithesis of a hitter like David Fletcher.

This year, over half of Fletcher’s batted balls have been classified as ground balls according to Fangraphs; this change is supported by Statcast data as well. Fletcher has done so at the expense of hitting less fly balls:

At a glance, Fletcher’s new batted ball distribution seems to be having a positive effect. Across 226 PAs, David Fletcher is hitting .325/382/.433 (129 wRC+), the first time he’s been above-average offensively. Plus, given Fletcher’s skills, the .356 BABIP he carries is more-or-less sustainable. 

On the flip side, we shouldn’t jump to conclusions. Are Fletcher’s increased ground balls benefiting him? Is hitting more of them at the expense of fly balls a good idea? 

For the average hitter, the answer is a resounding no. Doubles, triples, and home runs are usually the result of fly balls, so reducing them would translate to a loss of power. But remember – Fletcher is special. Because his exit velocity is so poor, his production on fly balls isn’t markedly better than his production on ground balls. And by poor, I mean consistently ranked near the bottom: 

The results make sense. In 2018, hitters’ fly ball exit velocity explained 75% of the variance (r^2 = 0.75) in fly ball xwOBA. Sabermetrics aside, the relationship is intuitive: the launch angle is already there, so the extra speed is what makes a difference. And since Fletcher’s fly balls don’t have much warning track power, most are doomed to die in the outfield. 

But how does exit velocity affect Fletcher’s results on ground balls? 

Yep, his production on ground balls is better than his production on fly balls! Of all major league hitters, this can only be said about David Fletcher, maybe Nick Madrigal. Furthermore, it seems as if a resurgence in exit velocity is contributing to a career-high in xwOBA (.255), as well as xBA (.263). 

However, the strong relationship between exit velocity and xwOBA exists differently in ground balls. Until they reach a threshold of approximately 86 to 87 mph, an increase in exit velocity does not have a significant impact on xwOBA or xBA. Once past that threshold, however, exit velocity is king once again. 

Using an extremely large sample, we can see this in effect. I’ve elected to use xBA as my measurement of production, since xwOBA is less meaningful when a majority of ground balls end up as singles. Over the course of the 2019 season, here’s how xBA changed when plotted against GBEV: 

So yes, ground balls hit over 87 mph matter – a lot more than you might have thought. And in 2020, David Fletcher has been hitting ones that matter, more than ever before: 

This alone is a satisfactory answer to our original question. But there are a few more ideas worth investigating. For instance, what if we considered his launch angle on ground balls? 

Common baseball sense suggests that lower launch angles result in lower hit probabilities, but spiked grounders do give infielders difficulty – the masterful slap-hitting of Ichiro comes to mind. So maybe the relationship isn’t linear. That turned out to be true, and a bit more: 

According to the plot, xBA decreases until the -7-degree mark, then reaches a local maximum at around -18 degrees, after which there’s a dramatic fall. xBA increases again at extremely negative launch angles, though weird bunt hits and mislabeled balls may contribute to this rise. Statcast does make mistakes. 

Based on what we know, an ideal ground ball is one that’s (a) hit at 87 mph or above, and (b) hit at either above 0 degrees, or in between -18 and -8 degrees. In addition to exit velocity, is Fletcher also optimizing his launch angles? 

For launch angle, the results are ambiguous. The increase in ideal ground balls could simply be due to the fact that Fletcher is crossing the 87 mph threshold more frequently. Still, this is still encouraging. However you choose to measure it, Fletcher’s doing an excellent job at hitting grounders. 

We can consider one last factor: batted ball location. This isn’t included in calculations of xBA, which are based solely on exit velocity and launch angle, but it’d be wrong to gloss over it – the difference between a groundout and a single is sometimes a matter of inches. Perhaps Fletcher is sending ground balls to the right places: 

What immediately stands out is the absence of batted ball ‘clumps’ in the 2020 spray chart. Fletcher is spraying his balls all across the field, a new tendency that could explain why he’s picking up extra hits. Here’s an example of said extra hit: 

Had it followed Fletcher’s usual pulled grounder trajectory, Matt Chapman would have scooped it up and delivered it to first. But Fletcher emerges victorious. 

But we might be getting ahead of ourselves here. It’s difficult to say whether or not Fletcher has refined his bat control, or if batted ball luck is playing a role. What if his ground balls are suddenly eluding defenders? We don’t have all 162 games for a correction to occur. 

However, that one caveat doesn’t invalidate his excellent 2020 season. His approach may seem like a faithful rendition of his past two seasons, but there are subtle changes. As they suggest, there is a strong possibility that his increased ground balls are not only elevating his production, but are also beneficial in the long run.

That’s consistent with modern baseball philosophy, which espouses the importance of players focusing on what they’re good at. Fletcher is good at hitting grounders, and he’s bad at hitting fly balls. So what does he do? Hit more grounders and less fly balls! It’s such an obvious solution that, unfortunately, didn’t become mainstream until analytics began to dispel the myths perpetuating all aspects of the sport. 

If he keeps this up, Fletcher is a likely candidate for baseball’s next perennial .300 hitter. Fletcher was already one of the more unique players around – this under-the-radar improvement might just cement his legacy. 

Follow P365 MLB and KBO Analyst Justin Choi on Twitter! @justinochoi

Follow us on Twitter! @Prospects365

Featured image courtesy of photographer Duane Burleson and Getty Images

All statistics from Baseball Savant and Fangraphs 


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