Going Deep: Definitely No Bummer

Nick Bucher explores Aaron Bummer's impressive performance in 2019, with an eye toward the potential for even more growth in 2020.

In the current MLB environment, plate appearances ending with strikeouts are becoming more and more common. Additionally, the 2019 season saw the trend of more and more homers being hit continue as well, something that is partially attributable to an alteration in the production of baseballs that resulted in a more tightly seamed and more “juiced” ball that traveled farther. Batters are getting better at capitalizing on this too, as an increasing number of hitters in recent years have been striving for optimized launch angle swing changes in recent years to get more batted balls in the air. The result has teams favoring more and more highly pitchers who can put up gaudy strikeout numbers and keep the ball out of play as much as possible.

However, one pitcher who is zigging while the rest of the league zags is Chicago White Sox reliever Aaron Bummer. Bummer certainly can get strikeouts, he racked up 60 of them in his 67.2 innings of 2019, good for an unspectacular but respectable 22.8% strikeout rate that he paired with a similarly acceptable but unspectacular 9.5% walk rate. Bummer is so fascinating though because of what happens when he does allow the ball to be put in play against him. This puts Bummer in rare company. When it comes to his ground-ball rate allowed, only Zack Britton’s 77.2% figure bested Bummer’s 72.1% in 2019. 


What Is Bummer Doing?


It makes sense that one great way to limit homers is to not allow balls to be hit in the air. Of course, since batters are getting better at improving their launch angles to drive the ball in the air, it’s much easier said than done to do this. That is unless you’re Bummer, who allowed a ludicrous average launch angle of -3.4. Yep, an AVERAGE launch angle under zero. The MLB average last year was 11.2. Bummer not only didn’t let many hitters launch the ball high in the air, but he also didn’t even let most of them hit it in the air at all! A launch angle of -3.4 is a ground ball, and with an infield defense that maximizes its abilities through shifting and positioning, it takes a lot of those batted balls to do much damage against Bummer.

Baseball Savant helps explain even more of just how bananas it is to be an opposing batter facing off against Bummer. To summarize what Bummer is boasting, he’s a left-handed pitcher who has a fastball velocity in the top third of the league and is also in the top third in the exit velocity he allows. His fastball doesn’t spin a ton, and he’s an average strikeout guy. Take a look at these red dots:

Bummer doesn’t care if he’s not striking out the world, because his expected batting average allowed (xBA) is in the 89th percentile, and his expected weighted on-base average (xwOBA) and expected slugging percentage allowed (xSLG) are in the 96th and 99th(!) percentiles respectively. Bummer is legitimately among the 1% when it comes to the expected slugging damage done against him.


How Is Bummer Doing It?


Bummer’s arsenal is fascinating, and while he technically has other pitches, it all starts with his sinker. Bummer’s sinker has movement unlike any other pitcher right now in the league’s does, as it has less horizontal movement on it than most do, and more vertical drop on it than most do, while also routinely being between 95-96 mph. According to Baseball Savant, his sinker drops vertically 31% more than the average sinker. Bummer’s sinker also breaks horizontally 20% less than the average sinker. The combination of those factors explains what makes him stand out from other pitchers with excellent sinkers and makes him so challenging for batters to prepare for during a plate appearance. Nobody else is doing quite what he is!

Let’s take a look at one particular game last June against the New York Yankees, where Bummer demonstrated just how filthy he can be. With regular White Sox closer Alex Colome getting the night off, Bummer was summoned to protect a 5-4 lead for a chance at his first career save. He opens the frame by frustrating Brett Gardner with the quality of the ball he puts in play to start the inning. Gardner had already homered earlier in the game and gets a pitch up and over the plate. Unfortunately, he can’t do anything with it except chop it right into the ground:



Clint Frazier was next up and picked up an infield single on a well-placed ground ball to shortstop. Bummer avoids getting frustrated with the BABIP gods, however, and proceeds to make Giovanny Urshela look completely helpless. Tough to even have a sub-optimal batted ball event if you don’t manage to put the 96 mph sinker in play, Gio:


Bummer is now 20 pitches into the inning, as he battles deep into a full count with DJ LeMahieu. He’s still completely in control though and earns that first career save by fooling LeMahieu badly. The infielder bails out and leans out of the way on 96 mph offering right over the plate:



One More “Grand”-al Point


Another factor that figures to play in Bummer’s favor significantly is the off-season signing of catcher Yasmani Grandal. Grandal is widely viewed as one of the league’s strongest pitch framers and will see the bulk of innings behind the plate for the White Sox this season. 2019’s primary White Sox catcher James McCann was a detriment to his pitchers as a pitch framer. Per Baseball Prospectus he cost his pitchers an estimated 8 runs with his -8.0 grade and his overall catcher FRAA (fielding runs above average) of -10.2. His adjusted FRAA (augmented with framing, throwing, and blocking contributions) was only marginally better, at -7.6. Grandal’s 2019 saw him as being worth 19.4 framing runs, while also posting an FRAA value of 20.1 and adjusted FRAA of 20.9. No matter how you view it, Grandal is going to be a huge asset to the pitchers he catches in 2020, including Bummer.

Per Fangraphs’ Pitch Values, Bummer’s sinker in 2019 was graded at an incredible 15.0. Even more interesting is that as mentioned earlier, he does have other pitches in his reptoire. Bummer has four other pitches that graded as slightly positive values too in his cutter (3.9), slider (2.1), four-seam fastball (2.4), and changeup (0.1). Bummer is already in short company by having so many options that aren’t problems, and if a few more of his secondary pitches to that sinker start getting calls and playing as significant positives, there may be even more room for Bummer to grow. Grandal’s elite framing figures to only help make that more possible.


Where Do We Go From Here?


Bummer signed a long-term contract earlier this offseason, so it is clear that the front office in Chicago views him as a key contributor on a team that is coming out of a successful rebuild with goals to compete in 2020. Bummer will open the season again in his role behind Colome as the set-up man for the White Sox, which theoretically renders him fairly uninteresting outside of fantasy baseball leagues that credit holds. The average fantasy baseball manager seeking saves from relievers looks right past Bummer, as evidenced by his ADP outside the top 400 picks in NFBC leagues from January and February.

But even if Colome does hold the closer gig all year, Bummer has plenty of deeper-league value purely with his expected excellent ratios. Combined with upside to pick up wins when pitching in close games,  and the fact that he’d be the heir apparent for saves if Colome does happen to struggle or get injured, then Bummer has a handful of paths to be a difference-maker. It’s worth noting as well, that Colome was the subject of trade rumors last summer.  Since he’s in the final year of his contract, Chicago may entertain offers for him again this year even if he is healthy and performing well, should the White Sox not be quite ready for a playoff run. At the absolute minimum, Bummer is somebody to keep an eye on in 2020, if for no other reason to enjoy his dope, dope sinker at work.


Photo by Quinn Harris/Icon Sportswire | Adapted by Rick Orengo (@OneFiddyOne on Twitter and Instagram)

Nick Bucher

Nick is a University of Maryland, Baltimore County (UMBC) alum, a lifelong Orioles fan, and a fan of all things baseball. He is smitten with fantasy baseball, both season-long and DFS, and will be elated when the O's win the 2029 World Series.

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