Astros Arm Comes Off IL In Need Of Strong Improvement Facing Mariners

Earlier last week, news broke out that Houston Astros rookie Tatsuya Imai was expected to be activated off the IL and start this Tuesday, taking the ball against the Seattle Mariners at home.

Ironically, the Mariners were the last team he faced, but on their home turf. In his last start, he indicated T-Mobile Park mound was too tough and the weather was cold, where his early beginnings to 2026 effectively fell apart.

Imai Dominant In Japan, Unable To Adjust Cleanly To MLB

The 2025 campaign Imai delivered for the Saitama Seibu Lions was a masterpiece, a prime reason why the Astros knocked on his door. He went 10-5 with a 1.92 ERA over 163.2 innings, leading the entire NPB in WHIP at 0.89 and finishing second in strikeouts with 178. He struck out a club-record 17 batters in a single game on June 17, and tossed eight innings of a combined no-hitter earlier that April.

By any measure, the command issues that had plagued him early in his career seemed solved. His walk rate dropped to 7.0%, down from a career average of 10.8%. Scott Boras, his agent, wasn't being hyperbolic when he said Imai had done everything Yoshinobu Yamamoto did in NPB.

The Houston Astros signed Imai to a three-year, $54 million contract last January as the expected crown jewel of their pitching after letting powerhouse and occasionally irritable Framber Valdez, who departed for Detroit in the off-season. They needed a workhorse. They needed a rotation anchor. They needed someone who could absorb 160 innings while the rest of the staff found its footing.

The projections for his MLB career were relatively optimistic. MLB Analysts compared his low-slot delivery and four-seam/slider combination to a younger Max Scherzer, noting similar pitch mix tendencies and elevated fastball approach. The Astros saw a pitcher who could average 94-95 mph on the heater while reaching 98-99 in high-leverage spots. For $54 million over three years, Houston felt like they had stolen valor.

What they got instead was a cautionary tale about the cruel gap between a pitcher's resume in one league and rookie shortcomings in another. Imai is by no means a project. Yet, moving halfway across the world, dealing with different sized baseballs and a lengthy schedule while adjusting to an altered eating schedule surprisingly translates to overall baseball performance.

The early signs were a mixed bag. In his MLB debut, Imai lasted just 2.2 innings, walking three and giving up four runs against the Angels. His second start was genuinely electric, throwing 5.2 scoreless innings against the Athletics in Sacramento, striking out nine, with 58 of 94 pitches for strikes. Maybe the first start was just jitters. Maybe the transition was just a bump.

Tragedy Strikes

Then came April 10 in Seattle. The wheels completely fell off, as Imai faced just eight batters and recorded one out. He walked four, hit one, allowed a run on a wild pitch, and forced in another by plunking Randy Arozarena with the bases loaded. He threw 17 of 37 pitches for strikes and did not record a strikeout. Out of the 13 swings the Mariners laid on his pitches, only one was a miss.

Imai was sent back to Houston the next morning on a possible injury. Keep in mind, this happened days after Hunter Brown and Cristian Javier went on the IL with shoulder strains. The arm fatigue diagnosis that followed was almost a relief at least it was physical, explainable and treatable. Imaging came back clean. There was no structural damage. Just a dead arm trying to adapt to a world it didn't recognize.

Rehab Scares

Following his minor road to recovery, Imai threw a couple rehab starts that unexpectedly added concern. At Double-A Corpus Christi, the 27-year-old allowed five runs on six hits in just two innings, with 31-of-59 pitches for strikes.

Triple-A Sugar Land was slightly better, but didn't merit confidence for an MLB return: one run in three innings inducing five walks with four of them issued in the third inning alone. When a pitcher can't throw it in the zone and can't get hitters to chase out of it, there is nowhere to hide.

The Astros lead the league in walks allowed this year, a prime example of their poor 2026 start. They sit last in the AL West, a division they recently owned for seven out of eight seasons. Their pitching staff carries a 5.97 team ERA that ranks among the worst in baseball. The bullpen, at one stretch, had a 7.08 ERA over 61 innings. The starters weren't much better, trading even at a 5.55 ERA over 60 innings.

Brown and Javier are not expected to return to the rotation until June. Lance McCullers Jr. at 32 years old, owed $17.7 million in the final year of his contract, coming off a 6.51 ERA in 2025 has been completely putrid in his so-called "healthy season."

Starting Pitching Coming Around

There are some bright spots forming in the rotation. Spencer Arrighetti, whose modest competence has been an unexpected lifeline, already leads the team in wins in just five starts with a sub-2 ERA. Peter Lambert has answered the call with his recent emergency starts. Mike Burrows seems to be finding his groove after his recent 7-inning shutout performance against the Cincinnati Reds.

On Tuesday, Imai will walk to the Minute Maid Park mound and face the Seattle Mariners, in an attempt to make a do-over and on the team give a floundering franchise something it desperately needs, which is a reason to believe this season isn't a wash.

The Astros remain, at least theoretically, alive. The AL West is mediocre enough that no team has definitively separated yet. Hader's return is six weeks away. Arrighetti and Lambert have given the rotation something resembling a floor. If Imai can find even a fraction of the pitcher who fanned 17 Lions batters on a June afternoon in Seibu Dome last year, Houston has something to look forward to.

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