How Tatsuya Imai Officially Stabilizes the Astros Pitching Rotation

The Astros made a big splash on New Year’s Day and started 2026 by stabilizing their rotation. With Framber Valdez likely leaving, Houston needed a quality pitcher behind current ace Hunter Brown and Imai fits that role. 

There is no doubt now that Houston has what it takes to be successful at the top of their rotation. Brown and Imai are looking like quite a formidable one-two punch for the Astros. 

Imai has pitched like an ace in Japan with a 2.18 ERA and 9.5 strikeouts per nine innings over the past three seasons. The 27-year-old has constantly been improving, and 2025 was the best year of his career. Imai went 10-5 and posted just a 1.92 ERA across 163.2 innings pitched with 178 strikeouts. 

2024 was just as impressive with a career high 187 strikeouts over 173 innings. Imai also won 10 games and put up a 2.34 ERA. He was an All-Star in both of these seasons. Across eight seasons with the Saitama Seibu Lions, he compiled a 58–45 record, a 3.15 ERA, and 907 strikeouts in 963.2 innings.

Astros Rotation Likely Set

The Astros now feature significant depth in the starting pitching department, led by Brown and Imai. 

“We feel pretty good about the rotation right now,” general manager Dana Brown said. 

Cristian Javier slots in as the likely third starter, who had a full offseason to further recover from his Tommy John surgery in 2024. Javier has long been a valuable member of the pitching staff and has come through in huge postseason games. He’s a formidable third option when he’s right. 

Spencer Arrighetti rounds out the top four after battling injuries in 2025. He has turned into a reliable starting pitcher for the Astros with a strong variety of stuff. Brown, Imai, Javier, and Arrighetti are truly a top four that Houston can rely on. 

The Astros are likely to go into a six-man rotation given the great depth they have at the position now. Houston recently acquired Mike Burrows from the Pirates in a three-team trade, sending top prospects Jacob Melton and Anderson Brito in return.

Burrows was the young, controllable starter with potential the Astros were looking for and slides in nicely as the fifth starter. Houston will likely have a couple of options for a sixth starter in the rotation between Lance McCullers Jr. and J.P. France. 

Even Jason Alexander is another name in the mix. Having six starters at the beginning of the year is a major advantage, and the Astros could be having an excess of riches when Ronel Blanco and Hayden Wesneski likely return from Tommy John surgery by late midseason. 

More on Imai

All the talent is there for Imai to be a top-line starter in the big leagues. The durability to pitch with close to 1,000 innings in the NPB and well over 150 in 2025 shows he can go deep into games and be a reliable option. The right-hander has six kinds of pitches in his arsenal, but primarily uses his four-seam fastball, slider, and changeup. 

While his average fastball velocity of 94.8 mph may not jump off the charts, being an average velo for a major league pitcher, Imai can turn up the heat and reach well into the high 97s-100 when needed. Imai uses his fastball 48% of the time, but also leans heavily on his slider at 33%. He boasts a 46% whiff rate on that slider. Imai’s changeup is also quite effective, and primarily uses that against left-handed hitters with a 41% overall whiff rate. 

Like many Japanese aces, the 5-foot-11 pitcher throws a splitter as part of his offspeed variety. Besides that, Imai uses the new-age “Vulcan” changeup and curveball occasionally. 

The Astros and their fanbase can now be much more confident in their pitching rotation thanks to this Japanese star taking his talents to Houston.