NPB’s Carter Stewart Jr fits 2027 Padres’ rotation needs
Image Credit - Prospects Live, NPB
San Diego is rumored to be addressing the starting rotation this offseason, with the potential departures of Michael King and Nick Pivetta casting a cloud of uncertainty over their 2027 outlook. Under AJ Preller, the Padres have shown a willingness to look overseas to find ways to address their rotation, and going to the well again could bear fruit.
With free agency coming up soon, it is no secret that the San Diego Padres have a dire need for starting pitching. Trade deadline acquisitions Casey Mize and Robbie Ray are likely headed elsewhere in free agency, as is 2026 mainstay Walker Buehler. Midseason addition Lucas Giolito will also likely see his contract option declined, sending him back to the free agent market.
Presently, the Padres’ 2027 rotation features some combination of Randy Vasquez, Joe Musgrove, and JP Sears. Yu Darvish remains on the roster as well, so he would be an option for the rotation as well despite some uncertainty regarding how ready he will be for Opening Day. The team will certainly need depth early on. Despite internal candidates such as Bryan Hoeing and Jhony Brito remaining, the upside with the two arms is limited. With the Padres aiming to contend, they could really use a Nick Martinez type to round out what is poised to be a solid pitching staff. But is there such an arm on the free agent market?
While Martinez himself is an upcoming free agent, the Padres have another option on the market that could bring the same swingman performance with upside and youth on his side.
If you watched the 2018 MLB Draft and followed the signing process, you might remember the name Carter Stewart. Drafted 8th overall by the Atlanta Braves, Stewart did not sign with the Braves due to concerns over his wrist, leading Atlanta to offer him a signing bonus below slot value. Stewart went the Juco route to be eligible for the 2019 draft, but shocked the baseball world by instead signing a six-year deal with NPB’s Fukuoka SoftBank Hawks.
It was an unconventional route for a player to take, and Stewart went on to pitch two seasons in the NPB’s Western League (NPB’s minor leagues) in 2019 and 2020 prior to making his NPB debut in 2021. Stewart returned to the Hawks’ big league club in 2023, pitching 77.1 innings with a 3.38 ERA, 3.79 FIP, and 79.5% left-on-base percentage. Stewart’s 14 starts led to him making a playoff start for the Hawks in the Pacific League Climax Series. His 2024 campaign was nothing short of brilliant, as the right-hander posted a 1.95 ERA, 3.00 FIP, and 1.08 WHIP in 20 starts (120 IP). Stewart struck out 105 while walking 51, with a 21% hard-hit rate.
If Stewart has pitched like this, why hasn’t he been signed by an MLB team? After the conclusion of his initial six-year deal, Stewart signed a two-year extension to remain with the Hawks, which covered the 2024-25 seasons and was valued at $9.9 million. Stewart’s 2024 would have set him up for a payday if that level of production.
However, his 2025 was not as expected. Stewart did not register game action as he missed most of the NPB regular season due to an abdominal muscle strain, with the nature of the injury wiping out his 2025 season. His 2026 campaign started on time, as he made the Hawks’ Opening Day rotation and was pitched in a total of 17 games. In 17 starts (14 with the Hawks), Stewart went 6-7 with a 4.63 ERA in 81.2 innings of work. The right-hander struck out 78 while walking 34. With the Hawks’ top squad, Stewart had a 5.23 ERA, but his 4.03 FIP indicated he was pitching better than the results. His season came to a close in August, as the right-hander departed his August 13 start with right knee discomfort.
Carter Stewart Jr. 🇺🇸 is back.
The 26-year-old missed all of 2025 with an abdominal injury. His current contract with SoftBank runs through the 2026 campaign.
https://t.co/VjJq8ZhFbB
— Yakyu Cosmopolitan (@yakyucosmo) February 3, 2026
Stewart’s free agency would see him enter the market at age 27 with over six seasons of professional experience, so he would not need to be posted by the Hawks to make the jump to MLB. His case is unique due to his age and experience, but the injuries sustained in 2025 and 2026 potentially muddle the waters about his free agent value.
The biggest question is whether there is a fit between the right-hander and the Padres. Stewart’s makeup as a starter is quite interesting, seemingly blending both American and Japanese pitching philosophies in his arsenal. Stewart is 6’ 6” and 230 pounds, so he’s got the physical makeup to be a starter in the league. His arsenal is a four-pitch mix, headlined by a 94-95 mph fastball that has touched 99 mph. His fastball is a lively one, as it features late rising action and high iVB that he uses to attack hitters at the top of the zone. Stewart’s fastball is significantly harder than the 91.2 mph average for an NPB fastball from 2024.
In his last truly full season (2024), Stewart used the fastball 48% of the time, using it to set up his two main secondaries. Stewart’s hammer curve has been a praised offering since his days stateside, as the right-hander’s mid-80s curveball showed borderline elite vertical drop. His curveball averaged 3286 rpm as an amateur, and continued to sit in that realm in NPB. For comparison, only two right-handed pitchers threw curveballs with spin rates at 3286 rpm or above, and the Mets’ Nolan McLean was the only pitcher to do so more than once. The fastball and curveball were Stewart’s calling card as a draft prospect, but his newfound split-finger has allowed him to elevate his game to the next level overseas. The splitter was a pitch he learned from the Hawks’ staff, and as he began to use the offering more often, it bore impressive results. Stewart’s splitter registered a 22.7% swinging-strike rate, as batters hit .098 against it through the first half of the 2024 season.
Stewart has also worked on incorporating a gyro slider into his arsenal, which would give the right-hander an offering with horizontal movement and late life to neutralize right-handed batters. The addition of a gyro slider would complement his existing arsenal, as it would tunnel well after a fastball. With Stewart’s high-iVB four-seamer, the gyro slider as an offering rounds out his arsenal and sets him up well to face lineups multiple times. There is one small caveat to all of this; much like with pitchers like Tyler Glasnow and even someone like Griffin Canning, the strong secondaries lose their effectiveness if the fastball cannot be landed for strikes earlier in the zone. Stewart’s 2026 struggles are partially attributed to falling behind early in counts, which allowed opposing hitters to lay off his secondaries and sit on the fastball.
Carter Stewart Jr. 🇺🇸 threw the ball with authority yesterday as he searches to find more consistency from start to start
He struck out 42% of left-handed hitters in the outing 👍
Final Line: 5.2 IP, 7 H, 2 ER, 2 BB, 8 K, 88 P, 17 Whiffs https://t.co/xZLuJV1hdT
— Yakyu Cosmopolitan (@yakyucosmo) June 12, 2026
There is also the concern about Stewart’s injury status. Hawks manager Hiroki Kokubo told the media back in May of 2025 that Stewart was set to begin rehabbing the injury, but he would likely be out the remainder of the year. Given that his injury was not arm-related, he would be a safer bet to take than a player coming off a shoulder or elbow injury, depending on how his recovery process has gone. His 2026 was not the best showcase of his potential, as he struggled to locate the four-seam fastball and was never truly himself. He performed well in three games with the Hawks’ farm team, but suffice it to say, Stewart was arguably never at 100% in 2026.
While the Padres are in dire need of rotation depth, they have been in this exact situation before and looked to the Hawks for reinforcements. Nick Martinez struggled through two seasons with NPB’s Nippon-Ham Fighters in 2019-2020 before breaking out with the Hawks in 2021, which led to his signing with San Diego before the 2022 season.
When it comes to the sort of contract Stewart could receive from San Diego, the parallels back to the Nick Martinez saga present a potential framework. Martinez’s first contract with the Padres, signed after the lockout in 2022, was presented as a four-year, $25.5 million deal when all escalators and one-year options were taken into account. The contract was essentially a year-by-year contract with successive player options. Martinez took home $2 million as a signing bonus and a $4 million salary for 2022, and the three annual options were valued at $6.5 million with a $1 million escalator if he made 20 starts in each season.
With Stewart’s track record not as sharp as Martinez’s in NPB’s highest league, his value could be hard to pinpoint. However, with the starting pitching market being as unpredictable as it has been over the past four offseasons (and more), a forecast for a Stewart contract could be something in the realm of a front-loaded five-year, $30 million contract with opt-outs after the second season, along with some form of escalators depending on innings pitched. This contract timeframe also aligns with the Padres’ window of MLB-readiness for top pitching prospects Coleman Borthwick, Kruz Schoolcraft, and Michael Salina, among others. While it would be an unconventional path to take for San Diego to go after an arm like Stewart, the Padres are the sort of team that can take this sort of calculated risk and continue developing the right-hander to his ace potential.
Eight years ago, Carter Stewart Jr. was projected as a potential first overall pick in the MLB Draft. While his journey through pro ball has been nothing short of unique, his potential return to MLB could give San Diego a young, quality starting pitcher for years to come.
A born and raised San Diegan, Diego Garcia is a lifetime Padres fan and self-proclaimed baseball nerd. Diego wrote about baseball on his own site between 2021-22 before joining the East Village Times team in 2024. He also posts baseball content on his YouTube channel “Stat Nerd Baseball”, creating content around trades, hypotheticals, player analyses, the San Diego Padres, and MLB as a whole.
A 2024 graduate of San Diego State, Diego aims to grow as a writer and content creator in the baseball community.