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Jake Arrieta has been fine

The results for the putative Cubs ace have been atrocious in 2017, but those have been more the product of bad luck and bad defense than any failure on his part.

MLB: Chicago Cubs at Boston Red Sox Bob DeChiara-USA TODAY Sports

It’s been a rocky follow-up season for the Cubs after their drought-smashing World Series victory last year. They’re currently 19–19, which is fine, but also a bit of a disappointment after an offseason that saw them elevated to juggernaut status. There have been lots of causes, to the extent that cause and effect can be neatly connected in MLB, but one has stood out more than others: the ongoing struggles of Jake Arrieta.

Arrieta, of course, was the Cubs’ golden ticket, the pitcher they acquired from the Orioles for next to nothing and turned into an ace. He broke out in 2014, with a 2.26 FIP/2.53 ERA, and won the Cy Young in 2015, with a 2.35 FIP/1.77 ERA in a whopping 229 innings. The recipe in those two ultra-successful years? Lots of strikeouts (a K-rate of 27.2 percent), not many walks (a BB-rate of 6.0 percent), and lots of grounders (a GB-rate of 53.3 percent, seventh-highest among qualified starters).

The last point was key. For all pitchers, grounders are generally good, as they rarely amount to anything more than a single and can often yield double plays. For a pitcher in front of the Cubs infield, featuring defensive standouts such as Addison Russell, Anthony Rizzo, and Javy Baez, grounders are especially good.

But since his Cy Young win, Arrieta seems to have gone from excellent to something substantially below that. Last season, the righty lost strikeouts and added walks, and ended up with a 3.52 FIP/3.10 ERA; still good, but not as good as he had been. And Arrieta’s 2017 is off to a terrible start, with a 4.17 FIP and a 5.44 ERA making him look like the pitcher he was before he came to Chicago.

The attempted diagnoses have been frequent, as a result. Our friends at Bleed Cubbie Blue asked “What’s Wrong With Jake Arrieta?” after his start on Sunday, while the Chicago Tribune wants to know “How can the Cubs fix Jake Arrieta?”. And Jeff Sullivan of FanGraphs wrote that “Jake Arrieta Has Not Been Good” on Monday, which the title does a good job of summarizing.

But any time there is a consensus, there must also be a hot take. I am here to shoulder the burden of delivering that hot take, and tell you that Jake Arrieta has actually been mostly fine.

Funnily enough, I don’t disagree with anything in Jeff’s piece. He goes into the mechanical changes that Arrieta has made, intentionally or not, and how they seem to have caused him to move away from ground balls and toward fly balls. I certainly can’t argue with the conclusion; Arrieta’s 2017 ground ball rate is 40.2 percent, lower than it’s ever been in his time with the Cubs. And while I’m not an expert on pitching mechanics, my friend and colleague Zack Moser has gone deep on Arrieta’s mechanics multiple times, and found that his release point has drifted, causing his command and deception to suffer.

I’m not here to disagree with any of that. Jake Arrieta today is a different pitcher than he was in 2015. But Jake Arrieta today is not nearly as bad as his ERA and FIP make him look, and still has the tools to be a totally successful pitcher.

If I was to break a pitcher down into component parts, I’d look at their strikeout rate, walk rate, and batted ball distribution, as I think those three pieces of information effectively communicate a pitcher’s style and effectiveness. Here’s how 2017 Arrieta has compared to 2016 Arrieta, and to 2014–15 Arrieta.

Versions of Jake Arrieta

K% BB% GB%
K% BB% GB%
2014–15 27.2 6.0 53.3
2016 23.9 9.6 52.6
2017 25.0 6.6 40.2

His strikeout rate: slightly below 2014–15, slightly above 2016, not very different from either. His walk rate: slightly higher than 2014–15, much lower than 2016. The biggest difference in Arrieta’s 2017 profile is simply that he’s inducing many fewer grounders, and many more fly balls.

Fly balls are not inherently bad. As discussed above, ground balls tend to do less damage when they turn into hits, but fly balls turn into hits at a lower rate than ground balls. In FanGraphs’ example data from 2014, fly balls turned into hits at a .204 clip, compared to .239 for ground balls, but yielded extra bases far more often.

As a result, with Arrieta’s move away from grounders and toward fly balls, we’d expect (in a vacuum) his BABIP to fall but his overall effectiveness to remain fairly stable. That hasn’t been the case: Arrieta’s 2017 BABIP is a whopping .355, compared to the miniscule .252 BABIP that he ran from 2014–16. He has the fifth-highest BABIP among qualified starters thus far in the season.

Similarly, the rate at which home runs turn into fly balls is not generally something starters can control, nor is it something that should change much based on how many home runs or fly balls a pitcher allows. But Arrieta’s 2017 HR/FB rate of 16.0 percent is nearly double his 8.1 percent clip from 2014–16.

Pitchers don’t usually have much control over either their BABIP or their HR/FB rate. But if Arrieta’s control is going south, and more of his pitches are ending up over the heart of the plate, he could be allowing more authoritative contact than he has in the past, which could in turn cause a rise in BABIP. That hasn’t been the case, though — Arrieta’s exit velocity allowed has remained elite, and even improved over 2016:

Arrieta’s exit velocity

Average EV Average EV on FB/LD LD/FB > 95mph per batter faced
Average EV Average EV on FB/LD LD/FB > 95mph per batter faced
2016 86.2 91.6 11.7%
2017 84.9 90.0 13.8%

In 2017, his average exit velocity ranks 308th out of 373 pitchers with at least 30 tracked balls, and his average exit velocity on fly balls and line drives ranks 309th. Elite, on both accounts. Thus, even with the decrease in his ground ball rate, he’s giving up only slightly more hard-hit balls in the air — certainly not enough to explain a 100-point jump in his BABIP.

So that’s one possible explanation: bad luck. And bad luck is more impactful on a fly ball, when it can turn a routine out into a double or even a home run, than it is on a grounder, when it turns outs into singles. This is certainly a possible downside of switching to a fly ball-heavy approach, but fly balls also benefit more from good luck, so it’s hard to say that this is something Arrieta should be blamed for.

But is that the answer we end up with, to the question that has been Jake Arrieta’s horrible 2017 performance? Not quite, and not just because ¯\_(ツ)_/¯ isn’t the most satisfying conclusion.

Earlier in the article, I mentioned that Arrieta’s ground ball tendencies were particularly well-suited to the elite infield defense of the Cubs. His shift to fly ball pitcher has come at a terrible time, as the regular outfield Joe Maddon puts out has changed from Jorge Soler/Kris Bryant in left, Dexter Fowler in center, and Jason Heyward in right to Kyle Schwarber in left, Albert Almora in center, and Heyward in right. I think Schwarber’s defense is underrated, personally, but I also think Almora’s is somewhat overrated. In any case, the net change to the outfield, of exchanging the defense of Fowler, Soler, and Bryant for Schwarber and Almora, has been a substantial negative:

This is another topic that Zack has written about, and he also connected it to Arrieta’s struggles. But I think it’s not just an explanation, but the explanation for why the former Cy Young winner has seemingly turned back into a pumpkin overnight. His strikeout rate, walk rate, and quality of contact allowed — the things a pitcher actually has control over — have all remained the same. What has changed? His ground ball and fly ball rates, along with his BABIP and the rate at which fly balls turn into home runs; the things a pitcher can’t really control, and that could be greatly impacted by a shoddy defense behind him.

Arrieta is certainly a different pitcher than he was in 2014 and 2015, and that’s cause for concern for Cubs fans. He was a truly elite starter, and if he can’t regain his groundballing ways, it seems unlikely that Arrieta will be able to regain that level of performance. But he also isn’t as different as his 5.44 ERA makes him appear. He’s still a talented pitcher, and even they have to endure bad defense and bad luck from time to time.

Henry Druschel is a Managing Editor at Beyond the Box Score. You can find him on Twitter at @henrydruschel.