Free Agent Profile: Tatsuya Imai, SP

Tatsuya Imai, SP

Position: SP B/T: R/R
Age: 27 (05/09/1998)

2025 Traditional Stats (NPB): 10-5, 1.92 ERA, 0.892 WHIP, 163.2 IP, 178 SO, 45 BB, 24G (5 CG, 3 SHO)
2025 Advanced Stats (NPB): 27.8% K%, 7.0% BB%, 2.01 FIP, 2.26 xFIP, 172 BAA

Rundown

What happens when you get Joe Ryan‘s fastball, prime Luis Castillo‘s slider, and multiple breaking ball and offspeed pitch shapes? Well, that potential is what three-time NPB All-Star Tatsuya Imai can bring to MLB. The Saitama Seibu Lions announced on November 10 that they officially posted Imai, opening the 27-year-old starter’s signing window, which comes to a close on January 2.

The most interesting part of Imai’s arsenal is his “wrong way slider.” This means that he pronates and forces the pitch to move to the arm side instead of the glove side. This pitch averages 86.3 mph with -2.4 inches of horizontal break compared to the MLB average of five inches of glove side break.

The concern with the pitch is how it translates to MLB. If that pitch loses too much of its arm-side break, it could be less effective. But if he can keep that movement profile, you could be looking at something very special. In the NPB, it had a 47% whiff rate and 41% chase rate. For reference, Castillo’s “wrong way” slider in 2022 put up a 41.4% whiff rate and 30.3% chase rate with about an inch less of horizontal break.

Imai throws a fastball with plus command at 94.8 mph. It features 13.5 inches of vertical break and 14.7 inches of horizontal break. This is very similar to Joe Ryan‘s profile, per Eno Saris of The Athletic. Ryan throws a 13.6 iBV fastball with 12.6 inches of horizontal break. Like Ryan, Imai throws from around a five-foot release point with an arm angle of around 20 degrees. It did not generate a significant whiff in the NPB at just 20%.

However, Yukyu Cosmopolitan broke down how Imai could increase his velocity in leverage spots with RISP. This suggests there may be more velocity to unlock. Jeff Passan of ESPN mentioned back in September that Imai experimented with a sinker, which may have brought down his tracked average fastball velocity. Eno Saris theorized that even if he loses some of his shape, he could still profile similarly to Luis Castillo‘s fastball but with more velocity.

It is unclear if Imai throws two different splitter shapes or if he throws a separate splitter and a split change. The constant is that he gets significant swings and misses at 38% with good chase at 33%. He generates significant movement with 15.1 inches of horizontal break. This complements his 5.4 inches of vertical break. Imai’s splitter rates as a plus weapon in his arsenal.

Per Yaku Cosmopolitan, against right-handed hitters, Imai throws his fastball and slider combo 92.2% of the time. Against left-handed hitters, he throws it 70.2% of the time, mixing in his changeup 16% of the time and his splitter 6.9% of the time. Last year, against left-handed hitters, his changeup ran a 40% whiff rate and a 34.1% chase rate.

Contract

MLB Trade Rumors predicts a six-year, $150 million contract for Imai. He won’t turn 28 until May, and because he is coming over from the NPB, he does not have the qualifying offer attached to him. Teams will have a posting fee to pay if they sign him, which would be around $24.375 million for a contract of this value.

Recommendation: Try to Sign

There is plenty of risk in Imai’s profile, but a lot of upside as well, which is something that describes pretty much all of the big free agent pitchers. The last NPB pitcher the Mets signed, Kodai Senga, has struggled to stay healthy after a spectacular rookie season. However, that shouldn’t deter the Mets.

Imai runs the risk of being a backend starter but has the upside of profiling as a number two in the rotation. If the Mets are confident they can maximize his ceiling, he may be worth the risk, especially at this contract prediction. Every contender is likely to be in on Imai, with the Phillies, Red Sox and Giants as possible bidding partners with the Mets, per MLB’s Jon Paul Morosi. He said recently he wants to beat the Dodgers, which rules them out (unless money talks, of course). The bidding will likely increase, and could very well reach the $200 million mark, which may make it difficult for the Mets to justify the risk.

In the end, Imai could have a higher ceiling than projected if he signs with the right team. Brandon Nimmo‘s trade proved the Mets aren’t playing around. They’re ready to win and take the steps necessary to reclaim a World Series title. That could start with signing Imai.

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