Astros May Have Unlocked Something in Tatsuya Imai's Arsenal

The Houston Astros saw encouraging signs after Tatsuya Imai expanded his pitch mix during Tuesday's win over the Miami Marlins.

Houston Astros pitcher Tatsuya Imai (45). | IMAGN IMAGES via Reuters Connect

The Houston Astros may have found the key to getting more out of Tatsuya Imai. After urging the right-hander to expand his pitch mix during the All-Star break, Houston saw encouraging early results in Tuesday's win over the Miami Marlins.

During his two-week break around the All-Star period, Astros pitching coaches met with Imai and encouraged him to use more than just his fastball and slider. The coaches had already discussed the idea with him during spring training, but they wanted to make it a bigger focus in the second half of the season.

Pitching coach Josh Miller reminded Imai about how he pitched in Japan last year.

"Just reminded him of his pitch mix in the NPB last year,” Miller said. “How we still think the slider is a special pitch, but he might need some other offerings to help it play up here. And maybe (it would) allow his fastball and his slider to play better if he used some other pitch types more frequently.”

Before Tuesday's game against the Miami Marlins, Imai relied almost entirely on his fastball and slider. He threw one of those two pitches 94.1% of the time during his first 13 Major League starts. He entered the game with a 6.06 ERA, and Houston's rotation ranked second-worst in the majors in ERA.

Imai admitted he focused too much on getting results during the first half instead of trusting his full arsenal.

“I think I was too focused on the result and … just trying to perform, so I wasn’t really thinking about the third pitch,” Imai said through an interpreter Tuesday night.

The Astros wanted him to bring back the splitter and changeup that he used in Nippon Professional Baseball. He threw only 54 of those pitches during the first half, including just 13 changeups.

Houston Astros starting pitcher Tatsuya Imai (45). | IMAGN IMAGES via Reuters Connect

Manager Joe Espada and Miller understood that Imai needed time to adjust. Besides facing stronger hitters, he also had to adapt to a different baseball and new environments throughout the league.

On Tuesday, Imai finally showed what the Astros hoped to see. He threw six innings against the Marlins, allowing four hits and one earned run while walking three and striking out eight. He needed 96 pitches, including 56 strikes, and generated 15 whiffs. Eleven of those came with his slider. He now owns a 5.59 ERA across 58 innings.

Imai also mixed in 12 changeups and splitters, all against left-handed hitters. That usage more than doubled the rate at which he threw those pitches during the first half, and Espada liked the change.

The Astros do not expect Imai to abandon his slider, which is still his best pitch. Instead, they believe a stronger mix of pitches will make both his slider and fastball even more effective. After weeks of stressing that message, Houston may have finally started to see the adjustment take hold.

Tuesday's performance was only one start, but it provided encouraging evidence that Houston's emphasis on expanding Imai's arsenal could help unlock a more consistent version of the right-hander.