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Consider Yusei Kikuchi Adjusted

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Yusei Kikuchi made all of the right changes.

MLB: Oakland Athletics at Seattle Mariners Jennifer Buchanan-USA TODAY Sports

Much was made of Yusei Kikuchi during the preseason. We saw a bump in velocity, and then there was a lot of talk about cleaning up his mechanics and tinkering with his pitches. With so many positives changes, it’s hard not to get too excited. Of course, most preseason storylines turn out to be for naught, because they’re either too speculative, or downright fallacious. Well, after watching Kikuchi on Saturday night, I think every bit of hype he received is deserved.

In March, our own Jake Mailhot wrote about how Kikuchi was in the process of reinventing himself. I bought into his changes, and so did Jake. It was pretty shocking to see how poorly Kikuchi pitched in 2019 for the Mariners, and he’s been interested in pitch design ever since his days in Japan, so it wasn’t at all unreasonable for me to think that Kikuchi could be significantly better in 2020 — especially with a bump in fastball velocity.

The preseason uptick in velocity has held thus far in 2020. Kikuchi’s fastball velocity, from 2019 to 2020, by game:

Obviously, that’s a significant, unprecedented bump in fastball velocity. At least for him. This is likely a result of the work he did to clean him his mechanics and shorten up his arm path, and it has had quite a ripple effect in terms of how it affected his fastball. Last year, Kikuchi ranked in the 25th percentile in active spin rate for fastballs at 78.0%. His raw spin rate already wasn’t great, but on top of that, he wasn’t throwing his fastball with good active spin (or spin efficiency), and so it didn’t get a lot of ride last year. But this year, he’s bumped his active spin rate all the way up to 93.7% thus far, which puts him in the 83rd percentile in the league.

So, to recap, that means Kikuchi has added velocity, raw spin, and active spin to his fastball. And that’s translated to much better ride on his fastball:

That blip at the end of 2019? I can’t speak to that. At least not with confidence. It corresponds with his highest release point of the year, so he could have just been doing a great job of getting behind the ball and spinning it well. Given that his spin rate didn’t spike in that game, it probably wasn’t sticky stuff. In any case, if you ignore that game, you’ll see that Kikuchi is getting much more ride on his fastball than the vast majority of his games in 2019. There were games where he did, but if we step back and look at the two years on the whole, he’s added an inch and a half of ride to his fastball in 2020. And that’s huge.

Here’s a fastball at the top of the zone from 2019:

And then another fastball, this time from last week:

Look at that! It’s beautiful. His fastball already played pretty well at the top of the zone — even without the velocity he has now. But now, he’s got a fastball that’s built to be thrown at the top of the zone. He’s still only thrown 61 fastballs this season, but in this minute sample, he’s increased his swinging-strike percentage from 6.8% in 2019 to 16.4% this season. That increase obviously isn’t going to hold, but some of it definitely will.

So with improved command and increased velocity, the cherry on top is that Kikuchi’s entire pitch ecosystem has changed.

Kikuchi’s pitches, plotted by velocity and spin axis:

2020 pitches are circled in green

I’ve circled Kikuchi’s pitches from 2020 in green. You can see that his pitches have all gotten faster, but some really key things are taking place. One of the most notable things is that his mid-80s slider has become a cutter that sits at about 93 mph. That’s a huge development, but we’ll get to that in a second. One thing that’s really flying under the radar is that Kikuchi has taken his old curveball and turned it into a much faster pitch that more closely resembles his slider from 2019. To put all of this as succinctly as possible: Kikuchi has essentially traded out his loopy curveball for a hard cutter. Given all of these moving parts, you can see why there’s such discrepancy in Kikuchi’s pitch classification between pitch tracking systems.

That brings us to the cutter. I told you we’d get to it! Kikuchi is throwing a hard cutter, and he’s throwing it a lot. The thing is, it’s pretty unrivaled. By velocity, Jacob deGrom throws an impossibly hard slider at 93.5 mph, but the next hardest slider or cutter for a starter is Kikuchi’s at 92.8 mph. By raw pitch usage, Dinelson Lamet has thrown his slider 88 times this year, and then there’s Kikuchi next, who’s thrown his cutter 72 times. So, he throws his cutter as hard as anybody, and he also throws it as much as anyone else too.

In 2019, half of Kikuchi’s pitches were bad fastballs. This year, he’s tampered his fastball usage to about 38% thus far, but now they’re good fastballs. And now he has a cutter that he’s throwing 45% of the time, and not only does it induce weaker contact than a four-seam fastball or sinker, but it gets whiffs, too. Add in that both are strike-getting pitches, and Kikuchi has raised his floor considerably.

Now, I’ve gushed about Kikuchi quite a bit here, and I think it’s fair to do so. But I want to offer a counterargument as well. And the argument is pretty simple: in his first game, Kikuchi wasn’t that great, and in his second game, Kikuchi looked damn near elite. As I see it, one reason is that the Astros are a better hitting team than the Athletics. Another reason, though, is that Kikuchi’s pitches looked different between his two outings.

I mean that in multiple ways. Kikuchi’s had a little less glove-side movement on his cutter against the A’s, and he wasn’t throwing it quite as hard. That’s definitely something we’ll want to keep an eye on — it’s not ideal if his velocity and pitch movement are oscillating from start to start. The other thing, though, is that he was locating his cutter much better.

Consider his cutter location in his first game of this year versus his second:

This is the key for Kikuchi. In game one, he was placing a ton of cutters to his arm-side. In game two, though, he was throwing them below the zone to his glove-side much more, which is where Kikuchi is going to get swings and misses, and where hitters will have a tough time barreling it up as well.

All it would take for Kikuchi to come back to earth is for him to lose a few ticks off of his fastball velocity. But for now, that hasn’t happened, and he’s got a fuller repertoire combat significant reversion if it ever does. It’s early to say, but it seems like he’s figured out how to better locate his cutter. If he keeps doing that, it’s hard to not be awfully bullish on Yusei Kikuchi.