Tatsuya Imai found a home before his posting window ended on January 2. Imai will reportedly join the Astros on a three-year deal, a move that’ll give Houston a groundball-heavy pitcher to replace the one lost to the free agent market.
A Look at Imai
Twenty-seven-year-old pitcher Tatsuya Imai will look to be the next “undersized” pitcher to excel at the Major League level.
The 5’11” Imai has been a major success story for the Seibu Lions over the last four seasons. Imai’s ERA bounced around between 4.00 and 5.55 between 2018 and 2020, when the new Astro was in his early 20s. However, he’s excelled since then.
Imai averaged over a strikeout per inning in each of the last four seasons, including in 2025. Arguably, the 2025 campaign was his best as a pro with Seibu. Imai struck out 178 batters over 163.2 IP, walked 45, and posted a career-best 2.5 BB/9. Additionally, Imai conceded only six home runs.
For Imai, the 27-year-old righty worked primarily with three pitches: a mid-90s four-seamer, as well as a mid-80s slider and changeup. Per official NPB recorded stats, Imai combined to use those pitches 90% of the time during the 2025 campaign.
Additionally, Imai also occasionally used a splitter and a slower curveball.
Imai is a shorter pitcher, so part of the game to focus on with him is the different look that he can provide. His fastball is more of a runner, a pitch that generated a lot of groundballs (49.1% GB%) and jam shots. It had a sub-20% Whiff% this past season.
His swing-and-miss pitchers are the slider and changeup. In the NPB, he used his slider against both left-handers and right-handers, while the changeup was more reserved against left-handed hitters.
Imai’s slider carried a 53.2% Whiff% against right-handed hitters (h/t NPB Pitch Profiler)
Per ESPN, the Astros will sign Tatsuya Imai to a three-year deal worth $63MM. The Seibu Lions will receive a posting fee for losing Imai.
Analysis
Imai will receive a hefty deal, albeit one on a shorter pact. His AAV will be the second-largest for a Japanese import, behind only Yoshinobu Yamamoto.
For the Astros, this is a move designed to beef up a rotation that needs the help.
Houston won’t have Ronel Blanco, Hayden Wesneski, or 2025 breakout pitcher Brandon Walter available for most, if not all, of 2026 as those three recover from elbow surgery. Additionally, Framber Valdez is a free agent and may have very well priced himself out of Houston.
Imai lines up to be a comparable replacement, one who, on paper, can match up very well in a ballpark that can be very friendly to right-handed hitters. In Japan, he generated a lot of groundballs, something that can work in his favor with Jeremy Pena and Carlos Correa — two adept fielding infielders — on the right side.
It also means the Astros can begin to piece together what the 2026 rotation will look like. Fellow newcomer Mike Burrows will join Imai and now-ace Hunter Brown, as well as Spencer Arrighetti and Nate Pearson.
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