Report: Astros Sign Tatsuya Imai

Dana Brown begins 2026 with fireworks

The Astros have reportedly come to terms with 27-year-old Japanese pitcher Tatsuya Imai, one of Nippon Professional Baseball’s premier pitchers.

There has been no official announcement from the Astros, likely due to the completion of a physical and/or a 40-man roster move to accommodate Imai’s signing.

Who is Tatsuya Imai?

Selected third overall by the Saitama Seibu Lions in the 2016 NPB draft, Imai debuted in 2018 at age 20.

Imai struggled with command early in his career and was eventually sent to the bullpen in 2020.

However, steady improvement followed and he posted sub-3.00 ERAs from 2021 forward, making three All-Star teams.

Imai had a breakout season in 2025, throwing 163⅔ innings, going 10-5, leading the league in ERA at 1.92, recording a 0.89 WHIP, and striking out 178 with only 45 walks (2.5 BB/9IP) and a 27.8% strikeout rate, the best among qualified NPB starters.

He pitched eight innings in an April 18 combined no-hitter and set a Lions record with 17 strikeouts on June 17.

Imai’s arsenal features a mid-90s four-seam fastball (touching 99 mph), a slider with arm-side run, a changeup, and a splitter, all delivered from a low release point.

The four-seamer averaged 94.9 MPH, which is a tick above the MLB average for RHPs (94.6).

His changeup, thrown mostly against lefties, has a 41 percent swing-and-miss rate.

Posted by the Lions in November 2025, Imai reportedly drew interest from the Cubs, Yankees, Mets, and Phillies, while other reports indicate the Mets were not sold on Imai as a top end MLB pitcher.

Represented by Scott Boras, who compared him to Yoshinobu Yamamoto, Imai prioritized a short-term, high-AAV deal with flexibility and that’s a deal the Astros could live with.

Imai will reportedly make a base of $18,000,000, with a $3,000,000 bonus if he reaches 100 innings.

If he reaches 100 IP in 2026, each subsequent season will be at $21,000,000.

The deal includes opt-outs after each season, allowing Imai to retest free agency, which, given Boras as his agent, he is likely to do.

For the Astros, facing the departure of Framber Valdez and needing rotation depth behind Hunter Brown, Imai represents a high-upside addition and the franchise’s most significant Japanese signing in years.

Houston is banking on Imai’s command, swing-and-miss stuff, and durability.

2026 Expectations

Imai immediately makes the Astros’ shaky rotation better, but the question is how much and will he be an Astro when (and if) it clicks?

The Fangraphs Steamer projections project Imai to an 8-9 record, 4.29 ERA, 4.22 FIP and 1.8 fWAR.

That seems low to me, as Yoshinobu Yamamoto posted a 2.9 fWAR, 3.00 ERA and 2.61 FIP in 2024 for the Dodgers and followed it up with a 5.0 fWAR, 2.49 ERA and 2.94 FIP last season.

In addition Imai’s 20.1% KK%-BB% would place him in the top quarter of the league, just behind Hunter Brown (20.4%) and in front of Dylan Cease (19.9%).

I’m not saying they are the same pitcher (even with Boras comparing the two) or will have the same success, but rather suggesting there may be an adjustment period for Imai.

With the opt-outs in his contract, he may well break out for another team in 2027 (assuming there’s a season).

On the other hand, some of the expectations and comparisons for Imai seem like a stretch, especially for a guy with an average MLB speed four-seam fastball (the speed topped the NPB league).

I’d spitball a guess somewhere between the two like a FIP around of 3.75 to 4.00 in 2026, but that’s a guess with no model or data to support it.

All in all, it’s a solid move for the Astros, a team in desperate need of arms and innings as the 2026 season draws nearer.

A durable arm in his prime with top-end command and upside is just what the doctor ordered, given the financial constraints Dana Brown is operating under.