What on Earth Happened With Jake Arrieta?

Tuesday was a good day for the Cubs. Most of them are good days for the Cubs, but on Tuesday, they earned their first win of 2017, edging out the Cardinals 2-1. Jason Heyward and Javier Baez drove in the runs, but the star was Jake Arrieta, who spun six innings with just an unearned run going against him. He piled up six whiffs, and it was a good way for him to get things going. If the Cubs have any potential vulnerability, it has to do with rotation depth. As long as Arrieta and the other guys are clicking, the Cubs are at least as good as anyone else.

On TV, Arrieta looked effective. In the box score, Arrieta looks effective. But what was the deal with his fastball? This is an open question. I don’t have an answer. I just have evidence that makes me think thoughts.

Here is one Jake Arrieta fastball.

91 miles per hour. Harder than I can throw! Here is another Jake Arrieta fastball.

90 miles per hour. Still harder than I can throw! But I’m no bar for a major-league pitcher. Arrieta should be compared against himself. That’s where the potential problem lies.

Things are kind of foggy right now. Velocity readings are being taken differently, and that’s causing some issues, since we’d all like to make sure we’re comparing apples to apples. The system that was spitting out 2016 velocities has been replaced by a different system, which tracks velocity as best as it can right out of the hand. As a consequence, we’ve seen a good number of pitchers in the very early going who appear to be throwing harder than they used to. That needs to be adjusted for. Just most generally, though, we don’t know what to make of 2017 velocities yet. We must all proceed with a certain amount of caution, if we’re going to dive into the numbers.

Just, let me show you a big table of numbers. This is a table of average fastball velocities. These are marks for all the starters so far in 2017, and you also see where they were in 2016. Jake Arrieta stands out, and not in a way anyone would like to.

Fastball Changes, Starters, 2016 – 2017
Pitcher 2016 FA 2017 FA Change Pitcher 2016 FA 2017 FA Change
Marco Estrada 88.1 90.2 2.1 Jon Gray 95.1 95.7 0.6
Madison Bumgarner 90.9 93.0 2.1 Ricky Nolasco 90.4 90.9 0.5
Kendall Graveman 92.7 94.7 2.0 Dallas Keuchel 88.6 89.1 0.5
Patrick Corbin 91.4 93.2 1.8 Jeremy Hellickson 90.1 90.5 0.4
Gerrit Cole 95.2 96.9 1.7 Clayton Richard 90.4 90.7 0.3
Adam Wainwright 90.3 91.9 1.6 Carlos Martinez 95.6 95.7 0.1
Tyler Anderson 90.9 92.4 1.5 Lance McCullers 93.9 93.9 0.0
CC Sabathia 90.0 91.5 1.5 Carlos Carrasco 93.8 93.8 0.0
Martin Perez 92.7 94.1 1.4 Jose Quintana 92.1 92.1 0.0
Scott Feldman 89.2 90.6 1.4 Chris Archer 94.3 94.2 -0.1
Kenta Maeda 90.0 91.3 1.3 Zack Greinke 91.3 91.2 -0.1
Yu Darvish 93.3 94.4 1.1 Ervin Santana 92.7 92.6 -0.1
Stephen Strasburg 94.9 96.0 1.1 Clayton Kershaw 93.1 92.8 -0.3
Edinson Volquez 93.2 94.2 1.0 Noah Syndergaard 97.9 97.6 -0.3
Masahiro Tanaka 90.6 91.6 1.0 Julio Teheran 90.9 90.5 -0.4
Sean Manaea 92.3 93.2 0.9 Rick Porcello 90.2 89.7 -0.5
Felix Hernandez 90.5 91.4 0.9 Corey Kluber 92.5 91.8 -0.7
Johnny Cueto 91.5 92.3 0.8 Junior Guerra 93.1 92.2 -0.9
Matt Shoemaker 91.5 92.3 0.8 Jon Lester 92.1 91.1 -1.0
Jhoulys Chacin 90.5 91.3 0.8 Danny Duffy 94.5 93.1 -1.4
Zach Davies 89.3 90.1 0.8 Jake Odorizzi 91.6 90.0 -1.6
Kevin Gausman 94.7 95.4 0.7 Hisashi Iwakuma 87.8 86.1 -1.7
Justin Verlander 93.5 94.2 0.7 Jake Arrieta 93.7 91.1 -2.6

The most important first point: I don’t know what to make of this yet. And, for all these guys, we’re talking about literally one 2017 baseball game. The present situation is complicated. But if there’s a normal error, it’s that 2017 velocities are a little too high. This group, on average, is throwing harder by 0.4mph. The median is +0.7mph. That would seem to reflect the different way velocity is being recorded. Arrieta is way off. This says he’s down 2.6 ticks. Compared to the average trend, he’s down more like 3.0 ticks. It’s too early for any measure of panic, but it’s not too early to wonder what’s happening.

Looking at the Tuesday Gameday window, the tracking system seems to have broken for a short amount of time. That’s suspicious! Arrieta, therefore, has some missing pitches. So does counterpart Adam Wainwright. That’s abnormal, so it can’t be ignored. On the other hand, look at the table — Wainwright is close to the top, at +1.6mph. In the same game where Arrieta’s reported velocities were down, Wainwright’s were up. And just for the record, this isn’t only about the fastballs. Fastballs just work as a proxy. All the pitch-type velocities changed.

Arrieta last night had 58 pitches tracked, according to Baseball Savant. The fastest was recorded at 92.6, and there were three pitches that cleared 92.0. Compare that to Arrieta’s first start from 2016, when he had 89 pitches tracked. The fastest was recorded at 96.0, and there were 51 pitches that cleared 92.0. I don’t know how many more ways to show you something looks weird. I can’t explain it, but I’d like an explanation.

Losing velocity isn’t good. We just went over this the other day, in discussing Zack Greinke. It doesn’t mean a pitcher is toast, but it reduces the margin of error, and it can certainly hint at something being mechanically or structurally wrong. And if you choose to dig into Arrieta’s Tuesday start a little deeper, you can see he threw fewer than half his first pitches for strikes. He threw barely 60% of his pitches for strikes, overall. Jake Arrieta ran into real command issues over the course of 2016, which somewhat lowered his stock. This is his contract season, and he’s looking to make a big splash.

I’d love to have an answer here. I’d like nothing more than to be able to tell you everything’s okay, or everything isn’t. In reality, we’ve had one start, and velocity readings have gotten all weird, and during this very Arrieta appearance, the tracking system temporarily stopped tracking things. I wouldn’t yet advise having any sort of strong reaction. Just, you should have *a* reaction. One game in, we’ve got some Jake Arrieta-related questions, which means one could question how strong the Cubs really are. Don’t take things too far, but at least be aware of the issue. If it’s real, it could be significant.

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Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

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David Spracale
David Spracale

I know during the broadcast the Len Kasper mentioned they were having some issues with velocity readouts in the stadium. Could be something or it could just be Arrieta throwing softer.


I hope he’s fine, but compared to what Wainwright was throwing…. I don’t know, doesn’t look promising.

David Spracale
David Spracale

Hey idiot read the whole article before commenting.


Great story. Compelling and Rich.

David Spracale
David Spracale

My bad everyone. I was responding to myself as the idiot for not reading the article.


Len commented that during an early, multi-inning stretch in which no velocities were being recorded at all.