While the impact of Japanese talent has played a role in MLB for decades, it has arguably increased over the past half-decade. A lot of that influence has to do with Shohei Ohtani. He is considered by many to already be one of the greatest players in the history of the game.
The talent continues to pour in from Japan, and the Houston Astros have now taken their first steps in that market in 2026.
The Astros made the massive signing of Japanese right-handed starter Tatsuya Imai at the start of the new year. Imai was one of the top names from Japan expected to join a major league team, and it was a bit of a surprise that Houston was the one that got him.
This was a big step forward for the Astros, who hadn’t gone down this pathway before. It ended up being a perfect fit for their rotation at the time. Houston signed Imai to a three-year, $54 million deal, and expectations remain high for him to perform in Space City.
While Imai quickly adjusted to Houston’s culture and had a great spring training with a 0.00 ERA in three starts (six innings total), it’s been a different story in the regular season.
The Start of Tatsuya Imai’s MLB Career
Imai just went 2 2/3 innings in his first start of the season at Daikin Park and gave up four runs and four walks. It was certainly going to take an adjustment period for the Kanuma, Japan native who had a lot of change to deal with, from the baseball to the mound to the catcher. The command was off with just 36 strikes in 74 pitches.
His second start of the season on the road against the Athletics was completely different. Imai went 5 2/3 scoreless innings and allowed only three hits. He struck out nine and walked three in 94 pitches, 58 of them for strikes. That was the kind of steady improvement expected for Imai during the beginning of the season.
Life is a highway.#ChaseTheFight pic.twitter.com/jDNCjFV4fG
— Houston Astros (@astros) April 4, 2026
The variety of pitches was a standout for Imai. He started deploying some of his additional off-speed deliveries besides his fastball, using his slider a lot more, as well as a few more change-ups.
The Struggles for Tatsuya Imai
A lot has changed since that great outing on April 4. There is now concern for Imai. He just came off an incredibly disappointing 1/3 inning outing against the Seattle Mariners. Imai could only get one out in his third MLB start. The reason was that he walked four and gave up three earned runs in that time, including a hit batter. There was no command, and Imai threw just 17 strikes in 37 pitches.
It continued to go downhill as Imai was asked after the game about his disastrous outing and said that the mound was difficult to adjust to. Although it’s only been three starts, it is a bit concerning that this has that much of an effect on his performance.
Through an interpreter, Imai said: “My impression for this stadium is the mound was really hard, so I wasn’t able to adjust to that mound.”
— Brian McTaggart (@brianmctaggart) April 11, 2026
NPB to MLB
The transition for Japanese pitchers to the major leagues is often quite challenging. There’s a lot more to deal with than the average fan realizes. It’s practically everything. The baseballs in Japan are different. Imai got used to that in spring training. The mounds are different. That is proving to be the biggest test so far. Not to mention the language, communicating with the catcher, and even the strike zones are more vertical as the American hitters tend to be taller.
Imai’s Injury
The worst news came in the last few days as Imai was sent down to Houston on April 11 for further evaluation for right arm fatigue. He was placed on the 15-day injured list for arm fatigue on April 13. Imai now represents one of the latest blows to the Astros starting rotation and will likely remain out for the rest of the month. A big update came out on April 14, and it was good news.
Imaging on Tatsuya Imai’s arm has come back clean and “positive,” Imai said through an interpreter. The team will try to increase his arm strength before Imai resumes throwing.
— Chandler Rome (@Chandler_Rome) April 14, 2026
The best of the best find ways to adapt and still become the incredible players they were back in Japan. The perfect pitching example of that is Yoshinobu Yamamoto of the Los Angeles Dodgers, who most recently won the 2025 World Series MVP. He threw a complete Game 2 of the World Series before closing out Game 7 on no days of rest after pitching Game 6. He also finished third in National League Cy Young voting.
More on Yamamoto’s Rise
Every Japanese starting pitcher coming in will inevitably be compared to Yamamoto, as he is now the gold standard. However, he also had his difficulties at the start of his MLB career. Yamamoto gave up five runs in his first major league inning and had just 23 strikes in 43 pitches. It seemed like he got used to the level of play after that, but still had his occasional struggles. Yamamoto also dealt with triceps tightness and missed close to two months.
Yamamoto overall posted a 3.00 ERA in his rookie season of 2024 in 18 starts with a 7-2 record. He truly took the next step in 2025 with a 2.49 ERA in 30 starts and threw 173 2/3 innings. That’s the kind of trajectory the Astros would like to see out of Imai.
Both players have unique talents, but Yamamoto was an absolute force in Nippon Professional Baseball. He won the Pacific League MVP for three straight years. Yamamoto also won the Sawamura Award (Japanese Cy Young) three straight times, as well as the pitching Triple Crown from 2021-23. The three straight MVPs matched the record set by Ichiro Suzuki.
Comparing Tatsuya Imai to Yamamoto
Imai was a three-time All-Star and an ace-level pitcher in NPB. However, it would be unfair to have the same level of expectations for him as for Yamamoto. Imai had a sub-2.00 ERA in 2025, while Yamamoto did that for three straight seasons before coming over to the Dodgers.
There is no doubt Tatsuya Imai can turn into an ace in MLB, but Yamamoto is a special talent who will be hard to match. The reality is that they are two 27-year-olds who are completely different pitchers.
Imai’s slider was the unique part of his arsenal. It swings the opposite way of how a slider is supposed to go. Hence the name ‘wrong way’ slider. That was employed at a high level against the A’s and posed fits to their hitters. It’s a pitch and delivery that hasn’t been seen before. The movement is incredible.
Tatsuya Imai’s Wrong Way Slider. 🤪
13 inches arm side run. pic.twitter.com/sFYc1Hm1tQ
— Rob Friedman (@PitchingNinja) April 4, 2026
Completely Different Pitch Use
Imai uses his four-seamer and slider the majority of the time, but also uses his changeup well against lefties and can also go to the Vulcan change. Besides that, a splitter and curveball can be thrown into the mix.
Yamamoto’s pitch mix is completely different. While he also uses the four-seamer, his splitter and cutter are used at much higher rates. The splitter is used well over 20 percent of the time. Yamamoto also goes to a curveball far more frequently at rates close to 15 percent. His cutter has increased use so far this season, and he also uses a sinker on occasion.
While the slider is Imai’s go-to, it’s Yamamoto’s least-used pitch at just 3 percent from last season. Besides that, Yamamoto also doesn’t deploy a change-up. The deliveries are also different, with Imai moving more towards a sidearm than vertical, like Yamamoto.
It will be interesting to see how Tatsuya Imai continues to develop his strength and endurance in the major leagues, like how Yamamoto did, and if he’ll be as effective as he was in NPB. The Astros will need it.
Main Photo Credit: Troy Taormina-Imagn Images
