How Have the NPB and KBO Signings Fared So Far?

Major League Baseball saw a number of high-profile names make the jump from Nippon Professional Baseball (NPB) and the Korean Baseball Organization (KBO) to North America this past offseason. These players ranged from potential superstars, to impact role players, to former MLB talent looking to make the move back to the big leagues.

The class of 2023-24 NPB and KBO free agents featured former league MVPs, pitcher of the year award winners, and several All-Stars.

With the first two months of the 2024 season in the books, these major leaguers (both new and returning) have found differing levels of success. Performances have ranged from award contenders finding wild success and surpassing expectations early on, to average performances meeting expectations, all the way to minor league depth struggling to find any sort of footing as they attempt to acclimate to MLB.

So, let’s take a look at just how each new MLB player from Japan and Korea has fared since signing their contracts.

Assessing the 2023-24 NPB Free Agent Class

Yoshinobu Yamamoto (LAD)

After Shohei Ohtani signed with the Dodgers, many eyes turned to the next big Japanese star in free agency: Yoshinobu Yamamoto. Soon after, the dynamic right-hander went ahead and joined his fellow countryman on the Dodgers, signing a 12-year, $325 million contract.

The Dodgers rotation was missing some key pieces on Opening Day with Clayton Kershaw, Walker Buehler, Dustin May and Tony Gonsolin all on the IL. This meant there were a lot of expectations placed on Yamamoto and fellow new Dodger Tyler Glasnow to perform until some of those names could make their return.

Yamamoto was one of the names frequently mentioned during preseason NL Rookie of the Year conversations. He posted a career 1.82 ERA and 0.94 WHIP across seven seasons in NPB, winning the Pacific League MVP and the Sawamura Award as the league’s top pitcher every year from 2021-2023. Yamamoto was supposed to hit the ground running.

However, his first start went as poorly as it could have gone, as the 25-year-old had his “welcome to the show” moment during the Dodgers opening series against the Padres in South Korea.

Yamamoto only managed to go an inning, giving up five earned runs in his debut.

He has calmed down significantly since then, as his ERA has dropped to 3.32. He also sports a 1.12 WHIP.

With a 6-2 record this season, Yamamoto has done exactly what any organization could ask of a starter, and that’s eat up innings. He’s managed to go at least five innings in every start since his rough major league debut.

Yamamoto has also been one of the league’s stronger starters when it comes to strikeouts and walks allowed. He is tied for 16th in MLB in strikeouts, placing him in the 82nd percentile in K% according to Baseball Savant. He ranks him 12th among qualified starters with 10.52 K/9.

As for walks, Yamamoto sits in the 84th percentile in BB%, having allowed only 14 walks across 65 innings of work so far in 2024. He also finds himself within the top 20 qualified starters with 1.98 BB/9.

Overall, Yamamoto has had a solid opening to his big-league career. He still ranks highly in the NL Rookie of the Year conversation, sitting second in betting odds (+600) according to BetMGM.

Shota Imanaga (CHC)

The only player Yamamoto trails in Rookie of the Year odds right now also happens to have made the move from NPB to MLB this past season, and that is Cubs southpaw Shota Imanaga.

Imanaga has been exceptional for Chicago this season after signing a four-year, $53 million contract. Up until a rough start in his last outing against the Milwaukee Brewers on May 29, he had not seen his ERA peak above 1.08.

Even so, he still sits with a sub-2.00 ERA (1.86) to go along with an even 1.00 WHIP, good enough to lead the NL Rookie of the Year odds at -120.

Imanaga has outperformed his career totals from Japan over the first two months of his MLB career. In eight seasons in NPB, he posted a 3.18 ERA and a 1.12 WHIP.

He also sits among the top contenders for the NL Cy Young, as he’s tabbed with the second-best betting odds at +425. This is in large part due to the fact he’s among the league’s best in multiple major pitching categories.

Imanaga sits in the 96th percentile in chase rate (35.9%), the 91st percentile in walk rate (4.3%), and pairs his sub-2.00 ERA with a higher but still impressive 3.01 xERA, which sits in the 83rd percentile.

So far, it’s safe to say the Cubs made an incredibly smart investment when they signed the 30-year-old lefty this past offseason.

Yuki Matsui (SDP)

When Yuki Matsui signed a five-year deal with the San Diego Padres, he came sporting a glistening track record out of the bullpen in NPB.

Matsui was a three-time Pacific League saves champion, including the two seasons directly prior to his move stateside. He also made five All-Star appearances.

Over a 10-season career in Japan, the 28-year-old lefty posted a 2.40 ERA and a 1.11 WHIP out of the ‘pen.

While he hasn’t had the same opportunities to close games this season as he did in prior years, he has been a solid piece for the Wild Card-hunting Padres so far.

Across 25.1 innings pitched in 2024, Matsui has posted a solid 3.91 ERA with a 1.26 WHIP.

He has found exceptional success with his splitter, which has only been hit at a .125 clip. And he’s yet to surrender a hit with his secondary breaking pitches, a sweeper and a curveball.

However, his four-seam fastball has been an issue thus far, as batters are hitting .304 off the pitch with a .279 expected BA.

Matsui has also had some trouble when it comes to surrendering walks and striking out hitters. He currently sports a 14.4% walk rate, putting him in just the sixth percentile. He has only mustered a 19.2% strikeout rate, which places him in the 29th percentile in the league.

Still, he has a solid whiff rate, ranking in the 82nd percentile at 30.2%, as well as a decent barrel rate, which sits in the 73rd percentile at 5.8%. His 87.6-mph average exit velocity sits in the 76th percentile.

Matsui has not looked like a dominant reliever who deserves the closer’s role up to this point, but he has been more than serviceable, providing the Padres with plenty of quality innings out of the pen.

Yariel Rodríguez (TOR)

The Toronto Blue Jays took a bit of a chance on Yariel Rodríguez when they signed him to a five-year, $32 million contract.

Rodriguez had a successful three-season stint in Japan from 2020-2022, posting a career 3.03 ERA and 1.23 WHIP.

However, he did not pitch professionally in 2023 after appearing for Cuba in the World Baseball Classic. While he was still under contract with the Chunichi Dragons, he did not return to Japan, eventually forcing the termination of his deal.

So far, it may be too early to tell what Rodríguez is going to be for the Blue Jays, as he’s made just four starts. This is partly because Toronto opted to give him a bit more run in Triple-A after spring training before calling him up on April 13. He then ended up going on the IL with thoracic spine inflammation on April 30 and has been out ever since.

Rodríguez has had mixed results so far. He was solid in his first two starts, posting 13 strikeouts and giving up just two earned runs across 7.2 combined innings of work.

However, he was only able to muster three strikeouts across his next two starts, giving up 12 hits and five earned runs across an identical workload of 7.2 innings.

His Baseball Savant page is pretty much all blue so far, featuring concerning stats like a 5.81 xERA, a .297 xBA and a 90.7-mph average exit velocity.

It has not been a great showing from the 27-year-old to start his MLB career.

He’s currently on a rehab assignment in Buffalo, and the Blue Jays will hope some of that magic he showcased in his first two starts returns when he is back at full strength.

Naoyuki Uwasawa (BOS)

Naoyuki Uwasawa has found his way onto the Boston Red Sox 40-man roster after being traded away by the Tampa Bay Rays, with whom he signed a minor league deal this offseason.

Across nine NPB seasons, Uwasawa posted a 3.19 ERA and 1.18 WHIP, being selected as an NPB All-Star three times. He was coming off of an All-Star season in 2023.

He’s currently at Triple-A Worcester and only managed 4.0 innings of major league work across two appearances last month before he was optioned.

In his extremely limited sample size with the Red Sox, he was pretty solid, posting a 2.25 ERA, but his underlying stats left much to be desired: a 4.50 BB/9 and a low strikeout rate of just 18.8%.

Uwasawa’s Triple-A numbers have also been underwhelming. He has a 5.77 ERA with a .271 average against in 34.1 innings pitched.

Assessing the 2023-24 KBO Free Agent Class

Jung Hoo Lee (SFG)

Jung Hoo Lee was the most exciting KBO free agent of the 2023-24 class and arguably the most exciting name in either the KBO or NPB classes not named Yoshinobu Yamamoto.

Lee, the 2017 KBO Rookie of the Year and 2022 KBO MVP, had a career .340 average and a .898 OPS in seven seasons in Korea.

So, when Lee signed a six-year, $113 million deal with the San Francisco Giants, it felt like they were potentially getting a top-tier outfielder.

Lee could still become that player, but his adjustment to MLB started slow, as he slashed just .262/.310/.331 with two home runs and eight RBIs before undergoing season-ending surgery for a torn labrum in May.

Over his first 158 MLB plate appearances, Lee found himself losing some of the signature approach he was known for in the KBO.

In his last three years in the KBO, Lee was a hitter known for his low strikeout rates, never reaching a K% above 6.8%. That translated to MLB, as he sat in the 99th percentile for strikeout rate, but his total did rise to 8.2%, higher than any season after his sophomore year in Korea. That’s to be expected, though, when a player is making the transition to a different league with a different style of play.

What is more of a noteworthy point about Lee’s plate approach is his inability to draw a walk. In his last five seasons in the KBO, Lee’s walk rate always exceeded his strikeout rate. In his MLB career so far, that has not been the case, as he’s only managed to walk at a 6.3% rate, lower than any total in his professional career. This puts him in just the 24th percentile in walk rate in the major leagues.

It also seems Lee could struggle to replicate numbers like the 23 home runs and .575 slugging percentage he posted in his 2022 KBO MVP season.

Lee sits in the 49th percentile in average exit velocity at just 89.1 mph, to go along with a 41.8% hard-hit rate and a 4.5% barrel rate, which place him in the 61st and 18th percentile, respectively.

And while his expected SLG of .416 sits higher than his .331 SLG, it’s a far cry from the .575 SLG he accomplished in 2022.

It’s still far too early to say Lee won’t work out in San Francisco, but the Giants will certainly hope that when he returns in 2025 he’ll be more like the KBO star they opted to lock up for six seasons.

Erick Fedde (CHW)

Moving along from the 2022 KBO MVP to the 2023 KBO MVP, Erick Fedde has been one of the few bright spots for the league-worst Chicago White Sox this season.

Fedde was a starting option for the Washington Nationals for parts of six seasons from 2017-2022 until making the move to the KBO. In 30 starts for the NC Dinos in 2023, Fedde posted a 20-6 record with a 2.00 ERA and a 0.95 WHIP, making him a legitimate return candidate. The White Sox rewarded his efforts with a two-year, $15 million contract.

So far this season, he has not disappointed them, posting a solid 3.12 ERA and 1.18 WHIP in 69.1 innings across 12 starts.

His advanced metrics won’t blow you away by any means, but he’s been largely solid across the board.

Fedde has a 3.43 xERA, a .231 xBA, a 7.6% walk rate and an 88.2-mph exit velocity against, all of which are above league average.

On a two-year, low-money contract, Fedde has exceeded expectations with his production over the opening two months of 2024. He could be a valuable asset for a postseason contender should the White Sox opt to move him before the July 30 trade deadline.

Woo-Suk Go (MIA)

It’s been a worst-case scenario situation for Woo-Suk Go over his first few months in a major league organization.

Go signed a two-year $4.5 million contract with the San Diego Padres this winter, but followed that up with a disappointing spring training.

He failed to crack the Padres’ Opening Day roster after surrendering 11 hits and nine earned runs over just 5.0 innings this spring (12.60 ERA). This was certainly nowhere near the 3.18 ERA and 1.27 WHIP he posted in his seven-year KBO career.

He was later part of the early-season blockbuster deal between the Padres and the Miami Marlins on May 4 that sent Luis Arraez to San Diego.

Weeks later, Go would be designated for assignment by the Marlins.

He has yet to make an appearance in the big leagues and could be on the lookout for another team after being DFA’d. Another organization will likely take a shot on him, as his minor league numbers have not been terrible early on.

While his 4.38 ERA and 1.46 WHIP with San Diego’s Double-A affiliate in San Antonio was not the start either party was looking for, he managed to put up a 3.00 ERA and 1.22 WHIP across 9.0 innings of work with AAA Jacksonville after the trade to the Marlins.

If he does get a shot with another organization in 2024, Go will need to work on lowering his batting average against; in both of his minor league stops, it exceeded a .270 clip.