This article was first published before Tatsuya Imai agreed to a three-year deal with the Astros on Thursday, per source.
Can Tatsuya Imai be the next Yoshinobu Yamamoto? The next great NPB-to-MLB ace, who goes from dominating in Japan to dominating in the Majors?
With Imai posted by the Saitama Seibu Lions on the heels of Yamamoto's heroic postseason performance for the Dodgers, that's one of the questions that jumps to mind, fairly or not ... especially after Scott Boras, Imai's agent, said of the top international pitcher on the market: "Certainly, he's done everything Yamamoto's done in NPB."
Whichever team signs the 27-year-old right-hander will certainly hope Imai follows the Yamamoto career trajectory. But when it comes to his actual pitching, Imai doesn't do the same things Yamamoto does. And he doesn't need to.
Imai -- who had a 1.92 ERA and 178 strikeouts in 163 2/3 innings for the Lions in 2025 and now wants to take down Yamamoto and the World Series champs in MLB -- can be a different kind of nasty pitcher from his countryman when he arrives in the big leagues next season.
Let's find some comparisons for what Imai might look like in the Majors.
1) He has a pitch profile like Luis Castillo
This is what Imai's pitch arsenal looked like last season in Nippon Professional Baseball (the data comes from this handy NPB pitcher profile app):
Imai has three main weapons: his fastball, slider and changeup. He throws those pitches from a low, sidearm release point, which gives his fastball and changeup a lot of horizontal movement -- both averaged about 15 inches of arm-side run in 2025 -- while his slider has more tight vertical break. (You can see a thorough breakdown of Imai's pitch shapes from pitching analyst Lance Brozdowski here.)
That stuff makes Castillo, the Mariners' three-time All-Star starter, a natural comparison for Imai: a low arm slot right-hander with mid-to-upper 90s fastball velocity, a fading mid-80s changeup and a sharp mid-80s slider.
The current version of Castillo has a lot of parallels to what you might see from Imai in the Major Leagues in terms of arm angle, velocity and movement.
Yuri Karasawa over at JapanBall, who offers a treasure trove of insight on NPB players, recently noted in a video breakdown of Imai that Imai and Castillo have a very similar pitch profile. And given Castillo's success as a workhorse with Seattle, that's a good thing for Imai.
If you're looking for a higher-end all-around comp for Imai at the Major League level, Castillo is the type of pitcher that best fits the bill.
2) He has a style like Max Scherzer
When it comes to how Imai deploys his pitches -- on top of just what his stuff looks like -- there are some other interesting MLB pitchers who take a similar approach. One of them is Scherzer.
Imai is fastball-slider dominant, especially against right-handed hitters. Over 90% of Imai's pitches vs. righties last season were four-seamers and sliders. Then he adds his offspeed pitches vs. lefties, going mainly fastball-slider-changeup (with some splitters mixed in, too). Those three pitches made up over 90% of Imai's offerings vs. lefties, and if you include the splitter, that's nearly everything he threw to opposite-handed hitters.
Scherzer is a good example of a big league right-hander who has that type of approach with a similar arsenal and an arm slot on the low side (though Imai's will likely be lower still). We're talking about the present-day version of Scherzer here, but even that version of Scherzer just had a postseason resurgence for the Blue Jays.
Scherzer is also four-seam and slider heavy vs. righties, with those two offerings accounting for over 70% of his pitches in 2025, and he's fastball-slider-changeup heavy vs. lefties, with those three pitches making up over 80% of his usage.
Imai wants to attack hitters in the same locations as Scherzer with those pitch types, too, most notably with the high fastballs that Scherzer is famous for. Imai said recently: "I focus on throwing a rising, high fastball from that low release -- almost like I’m driving it upward from below."
Pitchers like Castillo, or even Jacob deGrom, also have approaches like Imai generally, but Scherzer is all four-seamers, while Castillo throws a lot of sinkers. Scherzer's stuff at this stage of his career is more like Imai's, while deGrom is more sheerly overpowering. But we're just going for the same type of platoon pitch mix here, and this is what you'll likely see from Imai.
3) He has a fastball like Joe Ryan
Let's get into some comparisons for Imai's individual pitches, not just his arsenal as a whole. We'll start with the fastball.
Eno Sarris for The Athletic has taken a look at this already, using Imai's velocity and movement data and assuming he'll have an arm angle around 20 degrees, which would be among the most sidearm out of MLB right-handed starters.
Castillo's name once again comes up, but the strongest comparison is to Ryan, whose four-seamer is a big-time strikeout pitch for the Twins right-hander. Ryan got 109 K's on four-seamers alone in 2025, making him one of just four pitchers with 100-plus strikeouts on those heaters.
Ryan, like Imai, throws his fastball from a low slot (he had a 26-degree arm angle in 2025) with very similar induced rise (14 inches, the same as Imai) and run (13 inches to Imai's 15).
Imai's fastball has the potential to be like Ryan's, which would make it a very effective MLB-caliber heater. But there's also an X-factor for Imai in MLB: his velocity. Imai sat at 95 mph in NPB in 2025, but he showed the ability to dial up his four-seamer much higher than that.
In the Majors, pitchers tend to throw at their max velocity more often -- "emptying the gas tank," so to speak -- so there's a chance Imai's velo could even tick up, which could make his four-seamer an even bigger swing-and-miss weapon.
4) He has offspeed variety like Paul Skenes
Imai's slider is his best secondary pitch, generating a 46% swing-and-miss rate in 2025. But his offspeed is more interesting in what it shows about how Imai has tried to evolve as a pitcher over time.
First of all, it's noteworthy that Imai features a changeup first when he goes offspeed, not just a splitter, which is the signature of many Japanese aces, including Yamamoto.
Imai does throw a splitter, though, and has increased its usage in recent seasons as his strikeouts have also jumped up. And he now throws a new "Vulcan" changeup with a different wide grip, which he added during the 2025 season after learning it from one of his teammates. (The Vulcan changeup is sometimes classified as a sinker.)
Here's what those three offspeed pitches look like coming out of Imai's hand, as captured by Karasawa in his breakdown for JapanBall:
The fact that Imai throws three different offspeed pitches -- which all yielded whiff rates over 40% last season -- reflects a quality that is increasingly prevalent in MLB today: the ability to throw multiple pitch types within the same pitch group, whether it's multiple fastballs, multiple breaking pitches or multiple offspeed.
In 2025, the "Year of the Pitch Mix" in Major League Baseball, pitchers did that more than ever before, as they try to create an edge by expanding their pitch arsenals. Still, there are not a ton of Major League starters who throw both a changeup and splitter, let alone three offspeed variations like Imai.
Paul Skenes is the biggest and best example of someone who does, featuring both his splitter (aka, the "splinker") and a separate changeup. There are also a handful of others like Seth Lugo, or Yu Darvish, although they tend to use at least one of their offspeed pitches much more sparingly amid their sea of different pitch types. Shota Imanaga also threw both a splitter and changeup more regularly like Imai as a rookie in 2024, but he phased out the changeup in 2025.
Facing left-handed hitters in NPB last season, Imai threw 16% changeups, 7% splitters and 4% Vulcan changes. It will be interesting to see how he mixes and matches those varieties of offspeed pitches to attack Major League lefties.
5) He has a backwards slider like Trey Yesavage
There's one last unusual quality Imai has: That slider, his No. 1 secondary, often has "backwards" movement.
In other words, Imai's slider tends to move toward his arm side -- left to right -- rather than breaking to the glove side like nearly every other slider in professional baseball. And his slider can be very nasty.
One of the only MLB sliders that moves like Imai's is Trey Yesavage's. And we just watched that one dominate in the 2025 playoffs.
The Blue Jays rookie phenom delivers the ball nothing like Imai. Yesavage has one of the highest over-the-top release points in the Majors, while Imai will likely have one of the lowest. But their sliders share that one rare quality.
If Imai's slider keeps that same movement profile in MLB, it could add some deception against Major League hitters who aren't used to seeing sliders break that way. But it also could make the pitch something of a wild card. We'll just have to wait and see.