May 17th, 2020

xBA on Fastballs vs. Breaking Balls, Part 2

​As mentioned in a previous post, now is the time to look at some possibly overlooked players headed into 2020, based on their consistency in hitting both fastballs and breaking balls well.

As a reminder, here is what the scatter plot looks like. You can look up specific players using the "highlighter" feature on the Tableau Viz. 

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Expected batting averages on fastballs vs. breaking balls. Cody Bellinger hits both well.

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Green represents consistency on both types of pitches, or guys that kill fastballs so much that the gap in expected average on breaking balls is not something to be concerned with. Red represents a player that is bad at hitting fastballs, or has a wide gap in expected batting average between fastballs and breaking balls. Yellow represents a concerning gap between the two. Once we look at bucketing players into these different groups, we can then take the next step of seeing if there is a discernible trend in pitch mix. For example, as noted in last week's post, Justin Upton saw fastballs seven percentage points less in 2019 than 2018, and that could have contributed to his decline when he was on the field. Now, let's take a look at some players in the green bucket that may be getting overlooked.

J.D. Davis (NYM - OF)
Truthfully, this is a guy who probably isn't getting overlooked. Everyone is pining for the Mets to get him regular playing time with the universal DH coming to an empty stadium near you. Everyone knows that he is a Statcast darling, but his consistency on each type of pitch is astounding. 

DJ Lemahieu was the only other hitter to have xBA's above .300 in every type of pitch. That's some decent company. Now, I would expect JD's pitch mix to include more breakers and offspeed pitches going forward, given that barely anybody sees 60%+ fastballs anymore. At an ADP of 165, Davis is worth the 12-13th round pick with the universal DH. While there are reports that Davis may lose out on playing time even with the DH, and he still strikes out too much, expect him to play 90%+ of games in some capacity. When in doubt, pick the player with the best skills. Right now, that's Davis.

Alex Dickerson (OF - SFG)
Dickerson doesn't pummel fastballs (.286 xBA), but his minor dip on breaking balls (.256 xBA) means that he isn't likely to ever get into an extended slump. Dickerson's whiff rate on breaking balls is a way-too-high 33%, but his launch angle (12 degrees) and average exit velocity (90 MPH) make up for it. Launch angle is a function of getting out in front of the ball (Christian Yelich has a great explanation of it), so it's not a surprise that Dickerson whiffs a lot by trying to get out in front of the ball (and thus is early on breaking balls when he is expecting a fastball). To confirm this, he pulled 16 of his 33 balls in play against breaking balls - a limited sample, to be sure. Given that he is 29, he may not improve on pitch recognition. But, he could be a waiver wire pick up if he starts out hot and these trends hold. At an ADP outside of 600, there's no risk here.

Garrett Cooper (OF/1B - MIA)
If Cooper could just stay healthy, more people would know about his skills. Cooper's xBA on fastballs and breaking balls is an identical .273. However, he gets there in VERY different ways. While he doesn't whiff much on fastballs, his launch angle is 1 degree! He gets to this .273 through spraying the ball to all fields:

While those spray percentages are on all pitches, it's easy to see that Cooper's all-fields approach is a good batting average approach. As for breaking balls, his launch angle is more optimal (12 degrees), but whiffs at a 29% rate. Further, while that launch angle is better, his exit velocity is two miles lower on breaking balls than fastballs. Like Dickerson, expect Cooper's pitch mix to even out a bit more going forward. At an ADP of 413, you could get nearly 20 homers and a decent batting average out of him over a full season. If he plays most of the 60-game season, he will surely accumulate surplus value.

Tommy La Stella (3B - LAA)
Cubs fans shriek a little inside every time something good about La Stella pops up. His .314 xBA on fastballs and .300 xBA on breaking balls makes me do just that. His xBA's are fueled by tremendous plate discipline, whiffing less than 12 percent on both fastballs and breaking balls. His exit velocities and barrels are nowhere close to impressive, but he optimizes his launch angle to have a good batting average.

If La Stella reverts to his 2018 self, he is somewhat close to being Hanser Alberto. They have similar strikeout and walk rates, plus similar max exit velocities. La Stella barrels the ball a bit more, but its far from impressive. His 278 ADP is lower risk, but someone like Alberto is still on the board over over five rounds later.

Yandy Diaz (3B - TBR)
Yandy isn't the next Yelich quite yet, but his bat path suggests he has the capability to do just that. Specifically to this exercise, his high exit velocities on both fastballs and sliders yields high xBA's. His whiff rate is about league average on both pitches, and the only thing holding him back is getting more in front of the ball, resulting in a more optimal launch angle. Diaz will likely see less fastballs this coming year, but given that he hits all pitches so well, this shouldn't be an issue. If he can stay healthy, he should exceed that price.

Next Steps

There is certainly more to explore here, which starts with xwOBA on different types of pitches. As the season picks back up, tracking how the featured players in these pieces perform will be interesting. It takes a bit of time for expected stats to stabilize, and we may not be able to declare winners and losers of this exercise until after the season. Running some analytics on "xISO," or xBA-xSLG, is also intriguing. This would be similar to xwOBA, but with more of a focus on power. 

The main next step, of course, is actual baseball to be played!