What’s Up With Greinke’s Slider?

Zack Greinke goes to the mound today after giving up 13 runs in his last three starts, something he didn’t do at all last year. So we’re all trying to diagnose him. He is, too. We couldn’t figure it out together, really. Sorry to spoil the ending.

The slider is getting hit hard. Of his pitch types, it has the second-worst exit velocity so far this year, and it’s suffered the most from last year to this year.

Zack Greinke Exit Velocity by Pitch Type, 2016 vs. -15
Pitch Type 16 Exit Velo 15 Exit Velo Diff
FT 95.1 88.4 +6.7
SL 94.9 86.3 +8.6
FF 90.6 87.5 +3.1
CU 86.3 90.5 -4.2
CH 70.7 87.8 -17.1
SOURCE: Statcast

So something is amiss with the slider. Greinke admitted as much. “The first game, the slider was bad,” he told me before Tuesday night’s game against the Giants. “It was not good. The last two games, the slider has been closer to normal. It had no bite to it at all in the first game. The last game, it was pretty sharp. I still threw some back-up ones.”

A traditional look at his slider movement doesn’t produce a ton.

Zack Greinke Slider Movement and Velocity
Game Velocity Horizontal Vertical
2015 86.9 3.4 1.2
4-Apr 85.1 3.2 2.0
9-Apr 85.3 4.2 1.0
15-Apr 85.7 5.8 2.6

Yes, he’s gotten more side-to-side movement on his slider as the season has progressed, and it’s gotten the tiniest bit harder. But! It’s become less like his average slider from last year. It’s a bit more horizontal this year.

Let’s try another look, with the newer numbers at our disposal. Here are Greinke’s spin rates on his pitches last year and this year. See if you can spot the outlier.

Zack Greinke Spin Rates by Pitch Type
Pitch Type 2016 2015 Diff
Changeup 1855 1740 +115
Curveball 2498 2429 +69
2-Seam 2282 2096 +186
4-Seam 2390 2405 -15
Slider 1948 2314 -366
SOURCE: Statcast

Maybe his slider spin is off. Maybe it was just a few back-up sliders, though. Not every slider registers a spin rate, and this sample isn’t huge to begin with. We return to Greinke’s words. “I’m not throwing that good. Inconsistent. Last game I still threw some back-up sliders. Not something you want to do a lot. Just not quite there.” And he shrugged off any chance that offseason work was the reason. He “might have done a little less throwing than usual” but he should be fine soon.

For some reason, though, people aren’t swinging at his slider as much this year. You’d think, if it were bad, they’d swing at it more. But right-handers swung at 59% of his sliders last year, and that’s down to 53%, the biggest change in swing rates on any of his pitches.

Perhaps it’s location. “I’m throwing one more pitch middle-middle per game, which I guess is a lot but it shouldn’t make a big difference,” Greinke said. “The location hasn’t been as good, it just hasn’t.” This is how you can be bad with a pitch and still get fewer swings — Greinke’s misses with the slider are worse this year. His average location for a righty on righty slider has moved three inches downward, and that’s important. His average slider used to miss the outside corner down off the plate by 2.9 inches; this year it’s been missing by 6.3 inches. It’s easier to take a slider that’s low by a half a foot than one that’s just a few inches off the bottom of the strike zone.

In any case, batters are hitting him harder this year. Last year, he was 23rd in average exit velocity, and this year he’s 39th, and Russell Carleton just found that pitchers’ exit velocities stabilize after 50 balls in play… sort of. Greinke’s had 54 balls in play, and was a bit paranoid about his exit velocity given his results. His actual ranking reassured him. “There’s still work to do,” said Greinke, “but that made me feel better.”

Carleton also found that adding more data did not lead to better correlations for pitchers exit velocities past and future. The idea is that pitchers’ can affect their performance drastically from start to start and change their true talent, in effect. And that’s what Greinke is hoping to do. The park is “obviously tougher” but a little work on his slider location and bite, and he should be back to normal.

With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

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6 years ago

Maybe you just can’t throw sliders in Arizona. Sliders require air and humidity.

6 years ago
Reply to  descender

If that were true, you’d see two things:

1) It would show up in Park Factors for FIP, HRs, and so on. Chase Field is just about league average, maybe a tic above for HR, but dead even with Dodgers Stadium is just about every respect.

2) Air/humidity wouldn’t affect spin rate. It would effect the movement that spin induced, but not the spin itself.

6 years ago
Reply to  Rainmaker

Of course it affects spin rate. The ball is encountering friction as it spins, and the spin rate is calculated when, exactly? A picosecond after leaving the hand, or some time after that?

But anyway, thinner air wouldn’t reduce spin rate, so that can’t be the problem.