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Deciphering the Dynasty Value of Yoshinobu Yamamoto and Jung-hoo Lee

An in-depth breakdown of Yoshinobu Yamamoto and Jung-hoo Lee

Jake Maish
Dynasty 11/30/2023

One of the most difficult tasks in evaluating the free agent market each offseason is making sense of what we can expect from any players who are set to be posted from NPB, the professional baseball league in Japan, and the KBO, the professional baseball league in South Korea.

The level of competition in these leagues is very significant, and the competitiveness rivals that which we see in MLB games. But when players transition from the East Asian leagues to the American and National leagues, there are definitely some adjustments that have to be made.

The games are approached slightly differently from a strategy perspective, as the KBO and NPB both feature pitchers who throw more off-speed pitches (specifically splitters) and the hitters strike out significantly less. Plus, the actual sizes of the baseballs in MLB are slightly different. Beyond the gameplay, the players have to adjust to a new culture and a new language as well.

We’ll focus here on the most-anticipated free agent coming over from each of the two primary East Asian baseball leagues: Yoshinobu Yamamoto, a pitcher from NPB, and Jung-hoo Lee, a center fielder from the KBO.

 

Yoshinobu Yamamoto

 

The Arsenal

 

In this video, courtesy of Lance Brozdowski (@LanceBroz on X), you get a great look at Yamamoto’s fastballs. The four-seamer has great arm side run and works back beautifully to the edge of the plate to backdoor righthanders. The cutter moves in the opposite direction to keep hitters off balance.

Four-seam velocity: sits 95-97

Cutter velocity: sits 93-94

 

In this video, courtesy of Rob Friedman (@PitchingNinja on X), Yamamoto puts postseason standout Alek Thomas away with a knee-buckling splitter. The splitter is Yamamoto’s second most-thrown pitch behind the four-seamer, and sometimes he’ll even ramp up the usage to match or surpass the fastball.

Splitter velocity: Sits 89-91

 

In this video, courtesy of @tanaka13ver2021 on X, you get a great look at Yamamoto’s curveball and some more shots of the four-seamer. The curveball is sharp with incredible depth, and it’s his fourth pitch in the arsenal.

Curveball velocity: Sits 77-78

For some more info on Yamamoto’s arsenal, check out this article from MLB.com where David Adler breaks it down in a similar fashion but includes movement data and some awesome pitch comps to current MLB players.

I went back and watched Yamamoto’s two appearances in the 2023 World Baseball Classic, along with some scattered highlights from the NPB. In his WBC start against Mexico, he faced a group of strong MLB hitters that featured Randy Arozarena, Isaac Paredes, and Alek Thomas.

He’s extremely confident in all of his pitches, and he’s willing to throw them all in a variety of counts. He started at-bats with fastballs, curveballs, and splitters for strikes. He got chases with fastballs elevated or jammed inside to righties and with splitters that dove out of the zone at the last possible second.

The tunneling on his pitches looks incredible. Against Rowdy Tellez, he started the at-bat with a tailing four-seamer that caught the outside edge on the lower third. Then to put him away a few pitches later, he threw a splitter that looked destined to end up in the same spot before diving far below the outside corner. He follows sharp curves that drop in for strikes with devastating four-seamers that run right at hitters’ hands. It’s mesmerizing.

Considering all of this, I have to conclude that Yamamoto is comfortably a top-100 overall dynasty player. I would put him in the company of other starting pitchers like Jesus Luzardo, Bobby Miller, Pablo Lopez, and Tarik Skubal.

 

Words of Caution

 

You have to get pretty granular to find areas of Yamamoto’s profile to nitpick. When he faced Mexico in the WBC, he cruised for two innings before running into some command issues in the following inning. The first couple of batters he faced were able to work deep counts and one was able to draw a walk. I think this caused him to throw more pitches toward the heart of the plate instead of the edges.

His four-seamer can leak over the middle of the plate if he tries to throw it inside to lefties and doesn’t quite execute. The splitter loses depth if it’s thrown in the middle or upper third of the plate and can become more of a tumbling two-seamer. Yamamoto has excelled at limiting walks in the NPB and he can throw any pitch in the zone almost at any time. However, if hitters force him to live in the zone too much then he could be prone to allowing some hard-hit balls.

This general concept isn’t specific to Yamamoto. It’s a common mantra for hitters — make him throw it over the middle of the plate. So as far as weaknesses go, it isn’t incredibly impactful or worrisome. It’s more of an observation of how the earned runs happened back in March.

The obvious concern for Yamamoto, or any player coming to the US from foreign leagues, is the assumed adjustments that will need to be made and the unpredictability of MLB success for these players.

 

Predicting the Unpredictable

 

CJ Lu Sing, a current student at UC Berkely and the Head of Data Journalism of the Sports Analytics Group at Berkeley, conducted a linear regression analysis predicting MLB performance from NPB production and found that a pitcher’s ERA in NPB is significantly more predictive than a hitter’s OPS in NPB when it comes to foreseeing MLB production.

The correlation coefficient (r^2) of a hitter’s career NPB OPS to their MLB OPS is 0.14, which carries little to no meaningful correlation. But the r^2 of a pitcher’s career NPB ERA to their MLB ERA is 0.54, which points to a moderate degree of predictability. For a frame of reference, Dan Richards wrote this article for Pitcher List in 2020 where he found SIERA to be the most predictive ERA estimator. The r^2 of SIERA in year 1 to ERA in year 2 in this research was only 0.204.

There are some limitations to comparing these two studies. First is that Richards’ work featured a significantly larger sample size. Sing was only able to use data from the 13 pitchers who have made the transition from NPB to MLB since the current posting system was implemented in 1999, while Richards was able to include the full roster of MLB pitchers at the time. The second limitation is that Sing’s data compared career ERA numbers while Richards compared individual seasons.

The main takeaway here is that the more successful a pitcher was at preventing runs in the NPB, the more successful that pitcher was at preventing runs in MLB. And Yoshinobu Yamamoto is perhaps the most successful NPB pitcher of all time — he’s the second player in the league’s history to win the MVP in three consecutive seasons, and his 1.95 career ERA as a starting pitcher is the lowest of all time for NPB starters who have thrown at least 700 IP.

According to Sing’s study, we can reasonably predict that Yamamoto’s MLB ERA would fall right around the 3.20 mark. This is entirely based on the MLB ERAs of the 13 pitchers who made the transition from NPB to MLB between 1999 and 2022. Kodai Senga and Shintaro Fujinami aren’t included in this study because it was published on November 29, 2022.

 

Dynasty Value

 

Dynasty value is, of course, incredibly variable based on your league’s format and settings. So what I’ll do is focus on the most common fantasy stats for pitchers and what we can expect Yamamoto to provide for each.

ERA: As examined above, Yamamoto has shown incredible skill at limiting runs. It’s not unreasonable to bank on an ERA in the low 3s during his peak.

WHIP: Yamamoto carried exceptional walk rates each season that he played in Japan, and there’s no reason to believe that would change drastically in MLB. Kodai Senga was able to continually improve upon his walk rates as the 2023 season progressed, and his command was seen as the biggest risk in his profile before he was posted.

Yamamoto should have a walk rate of at least below 8%, which will bode well for the WHIP. Assuming a league-average BABIP and above-average walk rate, combined with the WHIPs he posted in NPB, we can expect he can safely post a WHIP less than 1.2, and maybe between 1.10 and 1.15.

Strikeouts: The league average strikeout rate in NPB is much lower than the MLB so pitchers tend to see an increase in strikeout numbers after making the transition. Given that Yamamoto’s K% was 26.4% in his career, I think we can be confident in him being able to post a 27-28% strikeout rate in the Majors.

This is also backed up by the statcast readings we got from the WBC. He posted a 13.5% SwStr against Mexico in 52 pitches in the WBC. This is obviously an extremely small sample size, but I use individual performances to evaluate minor league pitchers all the time. In prospecting, you have to be comfortable with small samples, and everything from the eye test to the arsenal data to the previous NPB transition trends backs up both the 13.5% SwStr and a potential 28% strikeout rate.

Wins: This will be largely dependent on the team he signs with, but we can be pretty confident that he’ll sign with a good contending team. The median Wins projection for a good pitcher on a good team is usually 12.

Quality Starts: Over his final three seasons in NPB Yamamoto averaged 7.1 IP per start, which is an exceptional number. The MLB season is of course longer and he will likely be pulled earlier than normal to build more stamina. For comparison, Yu Darvish averaged 8 IP/GS in the final three seasons he played in NPB and then he averaged 6.5 IP/GS in the first three seasons he played in MLB.

If you were to give Yamamoto the same regression in IP/GS as Darvish (I chose him specifically because his NPB stats and profile were the most similar to Yamamoto’s), then his projected MLB IP/GS could sit right around 5.95. So if he goes about 6 IP on average and allows 2-3 ER per 6IP on average, he could reach 18-20 QS in a healthy season.

One other aspect of Yamamoto’s value that is unusually high for a player being posted from the NPB is his age. Yamamoto is still only 25 years old, when most players being posted are at least 30 years old, or they’re closer to 30 than they are to 25. This definitely gives him a boost, as he’s just entering his prime and he should be able to perform at or near his peak for the next 3-5 seasons.

 

Jung-hoo Lee

 

The Singular Comp

 

In Jung-hoo Lee’s career in the KBO, he’s posted a triple slash line of .340/.407/.491 in 3,947 plate appearances. There have only been three other hitters who have been posted to MLB from the KBO, so we don’t have nearly as large of a sample to make comparisons from for what we can expect here.

Ha-Seong Kim is the golden example of success in this process, as he just finished off a breakout season for the Padres in 2023. Kim’s career slash line in the KBO was .294/.373/.493 in 3,664 plate appearances. And so far in his Major League career, he’s posted a .245/.325/.383 in 1,506 plate appearances.

Even though Lee’s slash line looks better and has a very similar slugging percentage, Eno Sarris pointed out this caveat that you can see in the batted ball data from each player’s days in the KBO.

This difference in quality of contact is definitely evident in the players’ home run totals from the KBO, as Kim more than doubled Lee’s HRs in a similar amount of PAs. Lee makes up the ground in the slugging percentage by hitting a metric ton of doubles. Lee averaged 35 doubles per season in his 7 seasons in the KBO. So while he won’t launch balls over the fence consistently, he could still provide some solid run production by finding the gaps in the outfield.

 

Dynasty Value

 

Again, as there are many different formats and styles for dynasty leagues, I think it’s best to approach valuations on a stat-by-stat basis.

Home runs: To add further to the discussion of Lee’s power, Aram Leighton pointed out on X that Lee makes a change to his approach in favorable hitting counts.

 

It’s always great to see players find creative ways to get to more game power than they might be able to provide with just raw power. Players like Isaac Paredes and Marcus Semien have made similar adjustments to look for pitches to pull in the air in favorable counts, and they’ve had great success at hitting for power consistently even though they don’t boast stellar exit velocities.

Judging by the batted ball data from Sarris’ tweet and the HR numbers Lee posted in the KBO, I think we would be thrilled to see a double-digit HR season from him in his peak years in MLB.

Batting average: This is definitely Lee’s most impactful statistical category. He’s only struck out in 7.7% of his PAs in his KBO career. Furthermore, in the article that Leighton teased in the above tweet, he pointed out that Lee carried a jaw-dropping 97% zone-contact rate last season. That would have easily been the best number in the Majors last season, with Luis Arraez coming the closest at 94%. Even with the increased pitching difficulty in MLB, those other-worldly contact skills should enable him to post batting averages consistently north of the .280 mark.

For an extremely well-researched and in-depth breakdown of Jung-hoo Lee, make sure to check out Leighton’s article here at justbaseball.com.

On-base percentage: All of the contact skills noted above definitely apply here, and it’s a nice bonus that Lee has a fantastic sense of the zone and walks more than he strikes out. If he can walk at a league-average clip around 8% of the time, then he should be able to post an above-average OBP of maybe .330-.335.

Stolen bases: Lee’s stolen base output in the KBO was incredibly consistent from 2017-2021 when he posted between 10 and 13 steals in each season. But then in 2022 and 2023 he cut those numbers in half and stole 5 and 6 bases in those seasons respectively. With the slightly bigger bases and pickoff limitations increasing MLB’s stolen bases last year, he might be able to get back to stealing double-digits in the Majors, but I would safely bank on 7 or 8.

Runs and RBI: This is largely team and offense dependent, much like pitching Wins, but his ability to secure consistent playing time and hit in a favorable spot in the lineup will also be huge factors. The good news is that he won five consecutive Gold Glove awards by being an exceptional defensive center fielder in the KBO.

Elite center field defense is something that the vast majority of MLB teams don’t currently have, so if he lands on a team that needs to bolster that side of the ball it could open a path to everyday at-bats, even if his offensive skills are slower to come around at first.

When it comes to where Lee might hit in a lineup, it’s hard to make an accurate guess of where we currently stand because we don’t yet know where he’ll sign and who he’ll be competing with for a good spot. But if Lee can maintain the incredible contact skills and hold his own in the slugging department, he’s a good candidate to hit in the 1 or 2 spots in a lineup that currently lacks that offensive profile.

Finally, for your viewing pleasure, here’s a short compilation of some great Jung-hoo Lee swings in the KBO.

 

 

Based on all of the information presented above, I would have a hard time ranking Lee as if he were a guaranteed everyday MLB player. I think there’s a chance he’s platooned against lefties or placed toward the bottom of the order and used primarily for his defense. Lee is also probably the best hitter we’ve ever seen come over here from the KBO, and that league can produce some incredible talent.

I think I would have Lee just inside the top 400 players overall for dynasty baseball, right around hitters like Brendan Donovan, Tim Anderson, and Michael Busch.

Photos by Wikimedia Commons, Rene Bohmer/Unsplash, and KBO | Featured Image by Ethan Kaplan (@DJFreddie10 on Twitter and @EthanMKaplanImages on Instagram)

Jake Maish

Jake is a fantasy baseball writer located in Cincinnati, OH. He plays most fantasy baseball formats but his favorite is H2H categories. When he's not watching and writing about baseball, he's playing board games with his girlfriend, Emma, or playing fetch and/or tug-of-war with their dogs, Moose and Daphne.

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