Kodai Senga was born in Gamagōri, a city in Japan’s Aichi Prefecture on the island of Honshu. A corner infielder until he began attending Gamagōri High School, his coach saw the strength and accuracy of his arm and saw Senga on the mound. The right-hander only pitched limited innings in high school during this transitionary time, but professional scouts took notice. On October 28, 2010, in the Nippon Professional Baseball Draft, the Fukuoka SoftBank Hawks selected Senga with their fourth pick in the Developmental Player Draft- a special phase of the draft in which teams select Developmental Players, players who are under contract to the organization but are not necessarily rostered on traditional minor league teams.
Senga did not pitch much in 2011, tossing only 3.3 innings in the fall Miyazaki Phoenix League, but used the coaching and facilities afforded to him by the Hawks to complete his transition from infielder to pitcher. Leg and shoulder injuries in high school left him unable to perform the rigorous and grueling training regimen Japanese baseball players partake in when he was first drafted, but by years end, the right-hander was in excellent shape. When drafted, the 18-year-old’s fastball topped out at 89 MPH, but by the time the 2012 season began, it was topping out at 94 MPH.
Senga spent the majority of the 2012 season on the Hawk’s ni-gun team in the Western League, but got his first taste of the big leagues, getting promoted to Fukuoka and pitching a pair of spot starts against the Chiba Lotte Marines in late April and early May. While the exposure to elite hitters certainly expedited his professional development, it was work that he did with Kazuki Yoshimi, a pitcher on the Chunichi Dragons known for his excellent control, earlier in the year that really put the right-hander on the path to greatness. Senga had thrown a split-finger fastball since high school and through working with Yoshimi he came to realize that by pushing the ball deeper into the interdigital folds between his index and middle fingers, not only would he be able to control it better, but he would also morph the pitch into a forkball, giving it more movement.
The right-hander had aspirations of joining the 2013 Hawks starting rotation out of spring training, but an ill-timed illness kept him off of the opening day lineup and when he was finally activated, he was assigned to the bullpen. His fastball-splitter combination stymied hitters, and by mid-April, manager Koji Akiyama appointed the 19-year-old set-up man to closers Ryota Igarashi and Brian Falkenborg. Senga appeared in 51 games in total, his season ending in early September due to an oblique strain, and posted a 2.40 ERA in 56.1 innings, allowing 32 hits, walking 26, and striking out 85. The right-hander was elected to the NPB All-Star Game and tied the Pacific League record for consecutive scoreless innings thrown by a relief pitcher with 34.1 innings.
Injuries would mar the next few years of Senga’s career. When he was able to get on the mound, he was still brilliant, but a right shoulder injury sustained in mid-June 2014 left him sidelined for nearly a year. In the 22.2 innings the right-hander threw in 2014, he posted a 1.99 ERA over 19 games with 17 hits allowed, 5 walks, and 28 strikeouts. In the 22.1 he threw in 2015, he posted a 0.40 ERA over 4 games with 9 hits allowed, 10 walks, and 21 strikeouts.
Senga finished spring training 2016 strong thanks to the addition of a slider to his pitching repertoire and manager Kimiyasu Kudo had seen enough to tentatively slot him in as a starter based on his body of work in the 2015 regular season, 2015 postseason, and spring training. The Hawks arguably already had the best rotation in the Pacific League, but Senga’s addition to the rotation even further bolstered the team’s pitching superiority. The right-hander made 25 starts and posted a 2.61 ERA in 169.0 innings with 125 hits allowed, 53 walks, and 181 strikeouts. He was just as good in 2017, earning his second All-Star Game nomination and being a major reason why the team won the Japan Series. Making 22 starts, Senga posted a 2.64 ERA in 143.0 innings, allowing107 hits, walking 46, and striking out 151. Following the conclusion of the Hawk’s successful playoff run, he asked to be posted to Major League Baseball clubs while negotiating his new contract but was denied.
The 2018 opening day starter, Kodai Senga was once again an integral cog of a dominant Hawks team that won it’s second consecutive Japan Series. Though he missed some time with right elbow and forearm tightness, he still made 22 starts and posted a 3.51 ERA in 141.0 innings with 116 hits allowed, 58 walks, and 163 strikeouts. While negotiating his contract after the season, he once again requested to be posted and was once again denied, with team president Yoshimitsu Goto telling the right-hander and the media that the Fukuoka SoftBank Hawks were against the posting system and would not be granting his wishes. The failed attempt did not sour Senga’s relationship with the team nor did it impact his ability to perform on the field, as he helped lead the Hawks to their third consecutive Japan Series championship by posting a 2.79 ERA in 180.1 innings with 134 hits allowed, 75 walks, and a staggering 227 strikeouts. Indeed, 2019 was by far the best year of Senga’s career. In addition to winning the Japan Series, he was named to his third All-Star Game, won the Pacific League Best Nine Award for pitchers, won the Mitsui Golden Glove Award for pitchers, and threw the Hawks’ first no-hitter since 1943, when the team was simply known as the “Nankai Club” after it’s corporate sponsor, the Nankai Electric Railway Co.
Leading into the 2020 season, Senga was dealing with aches and pains and would possibly have to start the season late, but the COVID-19 pandemic delayed the start of the season until June, giving the right-hander extra time to care for his body. He ended pitching 18 games and posted a 2.16 ERA in 121.0 innings with 90 hits allowed, 57 walks, and 149 strikeouts, winning the pitching triple crown. The Hawks won their fourth consecutive championship and Senga became the first pitcher since Yomiuri Giants great and Japanese Baseball Hall of Famer Tsuneo Horiuchi to make four consecutive Japan Series game one starts. Despite securing the Pacific League pitching triple crown and winning his second Pacific League Best Nine Award for pitchers and another Mitsui Golden Glove Award, the right-hander lost out to Chunichi Dragons southpaw Yūdai Ōno, who posted a 1.82 ERA in 148.2 innings, allowing 106 hits, walking 23, and striking out 148.
The 2021 season was a down year for both the 28-year-old right-hander and the Hawks themselves. In spring training, Senga was experiencing calf pain and then when the season began, he twisted his left ankle and damaged a ligament catching a comebacker, causing him to miss roughly the first three months of the season. When he returned, the Hawks handled him with kid gloves, as for the first time in years, the team did not seem to have their playoff ticket stamped. Skipping starts and managing the team rotation around him, Senga ended up making 13 starts, posting a 2.66 ERA in 84.2 innings with 60 hits allowed, 27 walks, and 90 strikeouts.
Following the conclusion of the season- the first season since 2013 that the Hawks failed to make the postseason, Senga signed a five-year extension with the team. The contract included an opt-out option after its first year to allow Senga, who would have accrued enough time to qualify for his international free agent option, to test the international market. The 29-year-old had another excellent season, posting a 1.94 ERA in 144.0 innings with 103 hits allowed, 49 walks, and 156 strikeouts, elbow tightness in May and a bout of coronavirus in August the only blemishes on his season. The right-hander did all he could to take the Hawks on his back and carry them into the Japan Series, but the team lost in the final stage of the Pacific League Climax Series against the eventual champions, the Orix Buffaloes. Following the loss, Senga announced his decision to exercise his international free agent option, becoming a free agent who could sign anywhere in the world.
Senga is on the smaller side for an MLB pitcher, standing an even 6’ tall and weighing 180 pounds. He throws from a three-quarters arm slot with a long arm action in the back. As is the tradition among most pitchers in Asia, Senga includes hesitation in his delivery during his leg lift just prior to his stride, but does not include a wrist wrap, another popular tradition among pitchers there. There is a bit of effort and violence in his delivery, and Senga has dealt with minor aches and pain constantly over the course of his NPB career, only once, early in his career, did he miss substantial time due to injury.
The right-hander has a wide assortment of pitches, throwing a four-seam fastball, two-seam fastball, forkball, cutter, slider, and curveball. In 2022, his fastball averaged 96 MPH, the highest of his career, topping out in the high-90s and even touching 101 MPH in a start in May. The pitch has some natural tail thanks to his arm slot and because of his size and release point, has a flat plane, giving it natural rise up in the zone. His two-seam fastball sits in the high-80s-to-low-90s and features more sink than most, as he uses a modified grip similar to his forkball, and almost like a hard changeup. He paces himself and does not throw every pitch at max effort, adding and subtracting velocity as needed. Despite the elite velocity, movement, and encouraging spin data, the pitches only grades as an average-to-above-average pitch because his command of it comes and goes.
Senga’s best pitch is his forkball. In 2022, half of his strikeouts came on the pitch, which has been nicknamed by fans and the media as the “ghost fork” because of the massive drop that the pitch has, causing it to disappear from the strike zone. Statistically, the ghost fork was the most difficult pitch to hit in the NPB in 2022, with a whiff rate over 50% and a chase rate over 40%. Masahiro Tanaka struggled to adapt his splitter to the MLB ball to a degree, and while Senga may have similar issues, the pitch is still likely to be a well above-average pitch.
The rest of Senga’s repertoire, his cutter, slider, and curveball, all exist on the same continuum and at times are very distinct pitches and at times bleed into each other. His cutter generally averages around 90 MPH, his slider generally averages in the mid-80s, and his curveball generally sits in the mid-70s-to-mid-80s, some slower and loopier and others faster and slurvier. The cutter and slider have similar movement profiles, with the cutter featuring slight horizontal break and the slider featuring slight horizontal break and slight vertical drop. Like his fastball, three elicit high swing-and-miss rates but his command of the pitches come and go and the right-hander gets batters to get themselves out by swinging at pitches outside of the zone.
In his career, Senga has only posted a first-pitch strike rate better than 50% once. He is generally fastball heavy early on, sometimes using nothing but his fastball against hitters. He begins attacking them with his breaking balls with more frequency the second time through the order, using his cutter, slider, and curveball to get into favorable counts and his forkball to put batters away- more than half of his splitters in 2022 were thrown in two strike counts.