Going Deep: Luke Jackson Has Not Been Lucky

Luke Jackson has been a lot better than you might think. Michael Ajeto demonstrates how he's been let down thus far in 2019.

As a Seattle Mariners fan, I have grown accustomed to my peers complaining about the team’s players. Their criticism is fair because the Mariners have spent many years being mediocre, with mostly mediocre players. Recently it’s become evident to me that I apparently know a fair amount of Atlanta Braves fans. The reason I’ve noticed is I’ve picked up on an inordinate amount of complaining about their closer, Luke Jackson. The Braves have spent a lot of time being a lot better than the Mariners—so you can imagine my annoyance to hear people complain about a closer with a 3.00 ERA and mid-2s SIERA. A player I have grown quite fond of is none other than Luke Jackson, but I have also found that Jackson is a very touchy subject for Braves devotees, and I’m not entirely sure why.

Case in point:



This isn’t a one-off tweet, either. Twitter search Luke Jackson and you’ll feel the full effects of the petty wrath of peeved fans, misled analysts, and fantasy owners.

On the surface, everything appears all well and fine. Jackson does everything good pitchers should do: He strikes hitters out a lot, he walks hitters sporadically, and his home run rate is about league average. When hitters do put the ball in play they hit ground balls two-thirds of the time. If you remove his first appearance of the year, his ERA drops from 3.00 to 2.13. So what gives?

Well, to be fair, Jackson has blown more saves than any reliever—he’s blown six save opportunities, so that’s annoying. I’ll concede that point, but I’m not convinced that Jackson’s blown saves were all his fault.


It’s Not Me…It’s You


By UZR, the Braves have the ninth-worst defense in the league. By DRS, they’re much better—14th-best. If we take the average of their defensive rankings (which is admittedly a super lazy way to do this), they’re something like the 18th-best defense in the league. So, we’ll say middle of the road, or slightly worse. But here’s where things get interesting.

Because Jackson is an extreme ground-ball pitcher, his ground-ball percentage ranks fifth in the league among relievers, I have a feeling his defense is letting him down when he’s inducing ground balls. On ground balls, Jackson has an xwOBA of .217. His wOBA is .305 on ground balls, though. That’s quite a discrepancy: Of pitchers with 50 or more ground balls, Jackson has the second-worst wOBA-xwOBA differential.

Of all batted balls, Jackson’s xwoBACON is .344—that’s 77th percentile. His actual wOBA on all batted balls is .411, though. That places him in the 29th percentile! Teammate Touki Toussaint has actually been more unlucky—his .077 wOBA-xwOBA is worse than Jackson’s .067—but Jackson has been unfortunate and good. Toussaint’s performance has been unfortunate and underwhelming. Notably, though, both have really suffered on ground balls. Toussaint’s .084 wOBA-xwOBA on ground balls is about as bad as Jackson’s .088. We can probably thank Dansby SwansonJohan Camargo, and Ozzie Albies for this. The trio have all put up negative DRS and UZR numbers on the year at their positions. To be candid, it’s not always wise to use DRS and UZR in small samples, as they take quite large samples to become reliable. The small sample size means we should probably take the Braves’ infield defensive numbers with a grain of salt no matter how much they support my hypothesis.

Another factor effecting Jackson’s result is his home park. After all, SunTrust park is the second-most conducive venue for runs in the MLB this year. At home, Jackson has a wOBA-xwOBA (on batted balls) of .053, while away it’s .072. So, if anything, Jackson has been helped out by his park. To me that suggests that the culprit here is the defense behind Jackson, or maybe Lady Luck simply has got it in for Jackson. I reason that it’s both, but the most compelling evidence is that his defense is letting him down. Another factor is the team: When utilizing a shift or “strategic alignment,” their wOBA is .357—eighth-highest in the league.

This year the expected batting average of all hits resulting in runs scored against Luke Jackson is .380. The home runs have all, more or less, been deserved. But when you look at the non-home runs, you start to feel for Jackson.

Here’s the most incredible statistic I could possibly present to you: Of 333 pitchers who have five plate appearances in which they’ve allowed a run, Jackson ranks 332nd in BA-xBA (i.e., his BA-xBA is second highest). To further drill this point home, Jackson’s .703 BA-xBA is also the second highest in the league, just behind David Hale’s .710. In other words, Jackson is in the 99th percentile in terms of bad “luck”, so to speak. Notably, Toussaint’s .581 also ranks 15th-highest.


The Proof’s In The Pudding


Let’s look at four of his at-bats that resulted in runs.

First, against Lorenzo Cain:




Here’s where the ball first bounced:



The expected batting average was just .058, but it resulted in a double, and it allowed the Brewers to tie the game. Blown save.

Next, against the Mets, with a comfortable lead:




Jackson induces yet another weak ground ball—its expected batting average was .063—but it again nets the opposing team a run.

And, again, here’s where the ball first makes contact with the field:



With two outs, Jackson induces a ground ball, fielded by Albies:




Expected batting average? .176

And lastly, an RBI from Kevin Pillar:




This may sound familiar, but here’s where the ball bounced:



And the expected batting average: .245.

At least in these examples, there isn’t a whole lot of bad fielding going on. There’s maybe some poor shifting, but mostly it’s unfortunate positioning and bad luck. When he’s not striking hitters out, Jackson is often putting the ball on the ground and crossing his fingers that his fielders can get to the ball and turn it into an out. That’s the goal of all batted balls, after all, but as an extreme ground-baller, Jackson is more susceptible to luck than almost anyone in the league. While an extreme fly-ball pitcher is more affected by unlucky home runs, Jackson is prone to base hits squeaking by his infielders.

Thus far I’ve mostly talked about how Jackson has been unfortunate, and how he’s blown a lot of saves. That doesn’t make him sound good, but these will: By SIERA, he’s been a top-10 reliever. By xFIP, he’s been a top-10 reliever. By FIP, doggonnit, he’s been a top-25 reliever! But he hasn’t always been dominant. Very recently, even, he was an afterthought in the Braves’ bullpen. So much so that he was designated for assignment almost exactly one year ago.


Spin Doctor


It’s unsurprising that Jackson is a Driveline Baseball disciple. He spent the offseason reshaping his slider, and it’s paid dividends. It’s always been a solid pitch, but now his slider is one of the best pitches. Of pitches thrown 200 or more times Jackson’s slider .177 xwOBA is 12th-lowest in the league, just short of Max Scherzer and Justin Verlander’s sliders, and better than that of Corbin Burnes.

It’s pretty incredible what Jackson has done with his slider. Last year his slider had above average vertical movement, and non-existent horizontal movement. This year he’s added a foot and half of vertical movement, sans gravity, and a smidge of horizontal movement.

With the added movement, Jackson has managed to increase the velocity of all of his pitches:



And as a Driveline participant you may be unsurprised to find that he’s honed the spin on all of his pitches as well:



On the year, Jackson had raised the spin rate of both of his breakers by 200, and his fastball by about 150. Jackson’s average spin rate has increased each month though it seems to have reached a plateau point.

Unsurprisingly, Jackson has used his slider more as its spin rate has increased:



Plan Of Attack


With these changes, he’s made very subtle adjustments. Against righties, he’s shifted his fastball towards his glove-side, away from hitters. He’s shifted his slider away too, but he’s also begun to use it to steal first-pitch strikes: In 2018, he threw 38 first-pitch sliders. This year, he’s already thrown 55. His in-zone swing and miss percentage have more than tripled, so this is a fantastic change that he’s made.




In 0-0 counts, Jackson has gotten a called strike 62.1% of the time when throwing his slider. Jackson has been stealing first-pitch strikes like taking candy from a baby. This is something he’s done to get ahead in counts.

Against lefties, he’s shifted both fastballs and sliders towards his arm-side, away from hitters. His approach has been even simpler here. Step one: Set up the fastball away. Step two: Bury the slider below it. The result? An amazing pitch tunnel with a lot of whiffs, and a lot of ground balls.

Here’s a perfect example, courtesy of Pitching Ninja:



Jackson has improved his ability to form a pitch tunnel—his in-zone swing rate is down on his fastball against both lefties and righties. You may notice that, by many metrics, Jackson is solid against batters, regardless of handedness. His xwOBA is far superior against righties, but it’s interesting nonetheless. One reason for this lack of a platoon split is that he has two pitches to show against righties, and three against lefties. While his numbers don’t currently look great against lefties, I think we should see his numbers improve throughout the year against them.


It’s clear that there’s a massive perception problem with Luke Jackson. It’s driven by six blown saves, a 1.26 WHIP, and a 23.5% HR/FB that’s more than double his career rate. It feels weird to trust Jackson, but there is a very small list of relievers that I would rather have closing games for my favorite baseball team. I can’t imagine a world in which this level of rotten luck persists, but I suppose we’ve seen far weirder things happen in baseball. Just the other night, the Cubs went three up, three down against Jackson. That’s exactly what he’s going to need to do for a while to give his sullied reputation a face-lift.

(Photo by Rich von Biberstein/Icon Sportswire)

Michael Ajeto

Michael writes about the Mariners at Lookout Landing, as well as here at Pitcher List. You can follow Michael on Twitter @dysthymikey, or you can not.

7 responses to “Going Deep: Luke Jackson Has Not Been Lucky”

  1. theKraken says:

    That is a pretty rosy take on Jackson. I could think of a pretty long list of players I would rather have closing for a contender. I don’t know anything about Twitter or the Jackson hate but I would imagine that it is pretty easy to find reasons to be positive about a lot of RP. If the luck goes the other way we probably are not pointing it out. Kind of crazy that there is always hate for the closer in ATL since Kimbrel left.

  2. AH says:

    Good piece. I’ve noticed the insane hatred of Jackson on Twitter (predicated on his past results, pre-Driveline), and I’ve been living in perpetual fear that the team will pull him from the closer role—because of the perception, not the performances. I just have to hope the Braves are smart enough to recognize what they have right now. Not trading for Kimbrel was a positive sign.

    • Michael Ajeto says:

      Luckily, I think they’ll leave him be unless he continues a 66% success rate in save situations. If they were gonna ditch him, they may have already done so by now. Long live Luke!

  3. The Truth Is Out There says:

    Hey Michael. Great work. It is really amazing how many people still judge baseball players by antiquated metrics. This article is a great illustration as to the difference in perception and reality.

    I was wondering if you cold let me know how you pulled that spin rate data from baseball savant? Is that a graph that already exists on their website or did you pull their data and make it yourself?

    Thanks so much.

    • Michael Ajeto says:

      Thank you!

      I got it from Baseball Savant. Go to the player’s page, click the Statcast tab, change whatever you want (e.g., I changed by season to by month) and click the button with three horizontal lines at the top right and download by png (or…whatever format you’d like it in!).

      • The Truth Is Out There says:

        thanks so much for the response! Appreciate it. Looking forward to more of your content. This was great.

  4. Moscowitz says:

    Jackson has been lucky

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