Be Bullish on Yusei Kikuchi

We now have reasons to be excited about Kikuchi.

The first two seasons for pitcher Yusei Kikuchi in the Major Leagues after arriving from Japan prior to the 2019 season have not gone all too well. His first season was an outright mess. With a minimum of 160 innings pitched, only Rick Porcello had a higher ERA, and the peripherals were somehow even worse. To go along with his 5.46 ERA, Kikuchi managed a 5.71 FIP. The elevated FIP was due to a poor strikeout rate, and an elevated home run rate. Only four pitchers struck out fewer hitters on a per nine basis than Kikuchi in 2019, and he also had a home run per fly ball rate that was among the ten-worst in the game. Yeah, outright mess sounds about right.

We’re not about to rehash the 2019 season though. Instead, let’s move forward to his second season. We can perhaps chalk up some of his 2019 woes to an adjustment phase that every player inevitably goes through, and maybe with some more time to get used to the environment, Kikuchi could’ve improved upon his ugly 2019 performance. It would almost be hard for that not to be the case, just considering the baseline from which he was starting from.

In 2020 his ERA improved… only slightly to 5.17. Well, that’s definitely not ideal. After two consecutive poor ERA seasons, the view of Kikuchi may suddenly be starting to shift to just being the type of pitcher that just never figures it all out. However, that doesn’t appear to be the case, at least right now. His more advanced metrics paint him in a much more flattering light, most notably his 3.30 FIP and 4.34 SIERA that suggest a much different pitcher than the one that had a 5.17 ERA. That’s the good thing about ERA-estimators, as we now have something to investigate.

As it turns out, Kikuchi did display some improved skills during the 2020 season that actually make him quite an interesting pitcher going into this season. These under the hood developments show a much different pitcher and one to perhaps be a lot more excited about. He’s still not perfect and there are still some things he needs to improve upon further to ultimately get to that next level, but Kikuchi is definitely more intriguing than his 5.17 ERA from last season suggests.


A Reworked Repertoire 


When it comes to Kikuchi’s pitch arsenal, there are three things that immediately stand out. The first thing, and probably the most important, is that Kikuchi added a new pitch, a cutter, to his repertoire. This new cutter also completely replaced his curveball as well. It seems like a good idea to ditch this pitch, as the curveball was not a great pitch for Kikuchi in 2019. It was his worst pitch in terms of wOBA, slugging, xwOBA, and expected slugging, and it was also the worst curveball by pVAL, clocking in at a -5.9 value.

Right away, the cutter made an impact. Looking at velocity, the pitch was one of the fastest cutters in the league, clocking in at 92.1 miles-per-hour on average. Compared to other cutters in the league, it was more middle-of-the-road in terms of swinging strike, whiff, and CSW rate, but compared to the pitch that it replaced, it was miles better by pretty much every metric:

Yusei Kikuchi – Curveball vs Cutter

That the CSW rate is higher for the curveball seems odd, it is due to a good helping of called strikes, but overall, the difference between the curveball and the cutter is pretty clear. The cutter got a lot more whiffs and was a lot less hittable. Maybe more importantly though, the pitch gave Kikuchi a better offering to approach right-handed hitters with.

Make no mistake, lefties hit Kikuchi pretty hard in 2019 as well, but righties were a different animal altogether. Righties hit .304/.359/.545 against him, with a .374 wOBA against. For context, that is essentially what Tim Anderson did overall at the plate in 2020. In terms of pitchers with at least 500 righties faced in 2019, Kikuchi had by far the worst wOBA allowed.

In 2020 though, Kikuchi’s wOBA allowed to righties improved tremendously, all the way down to just .299. Out of 37 left-handed pitchers with at least 120 right-handed hitters faced, Kikuchi’s .299 wOBA against ranked tied for 13th. A good reason for that dramatic turnaround for Kikuchi is due to the cutter. Righties did not fare too well against the pitch, as shown below:

Kikuchi’s Cutter Was Good at Neutralizing RHH

The table shows how Kikuchi’s cutter fared against righties compared to the pitch overall as well as to the 2019 curveball’s results also against right-handed hitters. The cutter was definitely an all-around improvement for Kikuchi, and a much better pitch to throw compared to the curveball, but the cutter was also extremely effective at helping him attack righties.

Kikuchi was truly missing a legitimate good option to go against opposite-handed hitters in 2019. With his curveball not working, he needed to adapt, and adding the cutter has, so far, been a good decision. 71% of the cutters he threw in 2020 were to righties, and the pitch was his most used pitch overall, showing just how important the pitch is to his repertoire.

The changes don’t stop here, though. The next area where Kikuchi was improved in 2020 is a bit more straightforward and has to do with his regular fastball, the four-seamer. To get right to it, the pitch added velocity. It’s always intriguing when it turns out that a pitcher has added a few ticks to their fastball, and in the case of Kikuchi, this increase was quite substantial. Looking at the biggest four-seam fastball velocity improvers from 2019 to 2020, Kikuchi is actually at the top of the list:

Biggest FF Velocity Improvers 2019 to 2020

Added fastball velocity is always a plus, but more velocity on its own is not always an indicator of better results. Instead, the benefit of more velocity as it relates to Kikuchi’s fastball is that the pitch ended up with quite a lot more movement. While the pitch is not the highest-spinning fastball on its own, clocking in at a rate that was in the 57th percentile in 2020, the pitch did generate a good amount of rise.

Kikuchi’s fastball averaged 2.1 inches of rise in 2020, which was good enough for 17th among pitchers that threw at least 250 four-seamers last season. This is also a stark improvement from where it was in 2019 when Kikuchi’s fastball barely had any rise at all. Additionally, this extra boost in movement had Kikuchi at the top of the leaderboards in terms of active spin rate, or spin that contributes to the movement of the pitch.

In 2019, Kikuchi’s fastball had an active spin rate of just 78%, meaning 78% of his fastball’s movement had to do with the spin. This was towards the bottom of the leaderboard in 2019. In 2020 though, Kikuchi was not only more efficient, but he was one of the most efficient pitchers in the game at optimizing his spin.  In terms of active spin rate, Kikuchi is towards the top of the leaderboard at 97%. For reference, Gerrit Cole, long considered the poster boy for active spin had a rate of 98% in 2020. Shane Bieber, one of the best pitchers on the planet in 2020, also had a 98% active spin rate.

Kikuchi was right up there with some of the best pitchers in the league, which is definitely an encouraging sign, especially considering where he started from. By adding both more velocity and active spin, Kikuchi’s four-seamer ended up with a 13.1% swinging-strike rate (ironically, this is identical to Cole’s), and miles better than his 7.5% swinging-strike rate from 2019. Here is a similar table to the earlier one, but this time, comparing his four-seamer year-to-year:

Yusei Kikuchi – Fastball Performance: 2019 vs. 2020

The differences should be pretty clear. The pitch generated more whiffs, and hitters weren’t able to do much damage to it and tee off on the pitch as much as they did previously.

As a result of both implementing the cutter as well as a greatly improved four-seamer, we come to the third and final most immediate thing that stands out the most about Kikuchi’s repertoire in 2020. This is one that is simpler. Due to the two big changes, we see a more subtle difference in pitch mix, most notably that Kikuchi’s slider usage rate decreased to almost half of what it was in 2019. His slider was his second-most used pitch in 2019, being used at over a quarter of the time. It’s usage dropped to just 16% in 2020.

Due to new and improved harder pitches, Kikuchi did not need to rely as much on his breaking ball, but the pitch still did play a role and was useful when he did throw it. It was his best pitch overall in terms of whiffs, and the pitch did add significantly more drop as well. It was used more so as a secondary offering to left-handed hitters, as he did not throw the cutter nearly as much when facing a lefty, and the pitch was ultimately a good change-of-pace pitch and a good way for Kikuchi to keep hitters honest last season.

Those three wrinkles added together shows us a much different pitcher than the one we saw struggle so mightily in his first go at it in 2019. Kikuchi went from having one of the worst whiff rates in the league to one that is comfortably above the league average, but that also doesn’t mean he deviated from the type of pitcher he is naturally. These changes are definitely a good thing, but they also work well with the type of pitcher that Kikuchi is when considering the batted-balls he allows.

It is important to keep in mind that Kikuchi is primarily a groundball pitcher. He doesn’t allow a lot of hard contact or barrels. In fact, his 3.9% barrel rate was in the 86th percentile, and seventh overall with a minimum of 150 batters faced last season. His groundball rate was also one of the 20-highest, checking in at over 50%. Additionally, the hard contact that Kikuchi did allow was, for the most part, kept on the ground:

Yusei Kikuchi – HH% by Batted-Ball Type

We see that not only did Kikuchi get the majority of his hard-hit batted-balls on the ground, but he did so at a rate that is well above the league average, and he was also quite good at limiting how hard his fly balls allowed were hit. He is close to average in terms of hard-hit line-drives but still better than average, and it is still a fine place to be.

Overall, Kikuchi’s profile of increased whiffs, keeping the ball on the ground, limiting barrels, and getting more of his hard contact allowed on the ground is quite a nice one, and that is primarily the reason why Kikuchi is an intriguing pitcher going into the 2021 season.


Where He Still Needs Work


That’s not to say that Kikuchi is now a perfect pitcher, because he’s not. We’ve been talking so much about the things in Kikuchi’s profile that have gotten better year over year, but one thing actually regressed from 2019 to 2020, and it is a big thing. His walk rate, at 10.3% in 2020, was an increase of over three percent from 2019. While not approaching Robbie Ray territory, it still was among the top-15 highest last season, and that is concerning. Let’s try to explain this elevated walk rate a bit.

The first thing to look at, and would probably be the biggest indicator is zone-rate. After all, throwing more pitches out of the strike zone usually leads to more walks, so this would be a good place to start. For Kikuchi though, it isn’t that easy. His zone rate year to year is only different by tenths of a percentage point. That’s not likely then to be a reason for an elevated walk rate, so some further digging is going to be needed.

It appears that Kikuchi’s zone rate differs greatly depending on the situation. To start, it seems that when Kikuchi fell behind in a count, he didn’t recover well.  Consider first-pitch strike rate, for instance. Here are the top-ten lowest first-strike rates in 2020 with a minimum of 150 batters faced, along with their walk rates:

Top-10 Lowest F-Strike%: 2020 with BB%

From this, we see that Kikuchi is third in this aspect, and notably only behind two rookies. Further, pitchers that “lead” in this department are generally ones with higher-than-average walk rates. As the old cliche goes, the most important pitch is strike one. It’s certainly possible for pitchers to work around a lower first-strike rate, but for Kikuchi, he was getting behind in the count early, and things seemed to snowball from there.

We can get into the real nitty-gritty about analyzing strike rates by each pitch count and really start the bombarding with numbers and where all those numbers compare to the league average, but that is probably delving into it too much. Instead, let’s just try to sum it up as easily as possible. The short of it is that Kikuchi was already working behind in the count after the first pitch of the at-bat, and when he was already behind in the count, he struggled to recover. This leads to him getting even further behind in the count and batters getting walked. This table should sum it up nicely:

Pitchers That Struggled to Throw Strikes in Zero Ball Counts

This table shows the ten pitchers with the highest rate of pitches called for balls when the count contained zero strikes during the 2020 season. As we see, Kikuchi is once again towards the top. There is also some overlap between the names featured on this table and the previous one, as it looks like Kikuchi wasn’t the only pitcher to struggle in this fashion last season.

Also notable is that Kikuchi threw 43.3% of his total pitches last season when in a zero strike count, which was 15th in the league, and also had a top-30 rate in terms of percentage of total pitches thrown when behind in the count. So, we know that Kikuchi struggled to throw first-pitch strikes, and then from there, he struggled to get back into the count, which contributed to him losing more hitters to walks, and thus, the elevated walk rate. Simply put, Kikuchi needs to start throwing more strikes, especially when he is already behind in the count for him to truly reach his full potential on the mound.




All in all, when evaluating Kikuchi’s 2020 season, it is important to look beyond his ERA. ERA matters, of course, but we all know that ERA is not the best measure of a pitcher’s true performance and weird things can happen that influence a pitcher’s ERA, especially in the small samples from the 2020 season.

Kikuchi was a better pitcher last season, and while it only led to a marginal improvement in ERA, the improvements he did make show themselves in other metrics, including the ERA indicators and estimators. It seems a little basic to just look at these estimators, such as FIP or SIERA, and suggest that a pitcher was purely better based on that alone, but fortunately, in the case of Kikuchi, he was better and there is evidence for it.

Kikuchi reworked his repertoire almost completely. Adding a new cutter to the mix that almost immediately became one of the best pitches in its class is good enough on its own, but also helped him approach right-handed hitters in a different and better way. That area was one of his biggest struggles from 2019, but he greatly improved on it the next year. It also gets even better considering his regular four-seamer added a good amount of velocity and rise, which helped baffle hitters, especially so when in 2019 the pitch did very little of that baffling.

It would be possible to suggest that some of this can be chalked up to those pesky small sample sizes that mess a lot of things up that were referenced earlier. While that can be possible and it can also be possible that some of these improvements may be exaggerated a bit because of the small sample, there is still little doubt that the improvements were there from Kikuchi last season, and that they were impressive. Kikuchi is still not at his full potential. He can still stand to improve upon his control and command, but overall, Kikuchi was a different pitcher in 2020 and is one to be bullish on in the future.

Photo by Leslie Plaza Johnson/Icon Sportswire | Adapted by Doug Carlin (@Bdougals on Twitter)

Matt Wallach

Matt studied accounting at UAlbany, is a Yankee fan, and writes for Pitcher List and Rotoballer where he can work with even more numbers to analyze baseball players, which is a lot more fun.

2 responses to “Be Bullish on Yusei Kikuchi”

  1. tom says:

    I would love to peruse the zero strike percent statistics, where should I go to look at the data?

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