Detroit Tigers right-hander Casey Mize saw manager A.J. Hinch emerge from the dugout, took a walk behind the mound and gave the ball away with two outs in the fifth inning of Thursday's 7-4 win over the Colorado Rockies at Comerica Park.

The 27-year-old had only thrown 66 pitches.

He had more gas in the tank.

"I was mad at myself," Mize said after Thursday's game. "The outing didn't end the way I wanted it to. The pitch count was low, too. I feel like I could have gotten way more outs and done more for our bullpen, but I just couldn't get out of the inning. Just frustrated with myself."

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Mize, who has a 4.47 ERA across 94⅔ innings in his fourth MLB season, didn't complete the fifth inning because the Tigers didn't want him to face Ryan McMahon for a third time, but that doesn't mean his 19th start of the season was a bad start.

It was actually one of his better starts — until the end.

"I thought he responded well to the first sign of adversity (in the second inning)," Hinch said after Thursday's game. "It looked like he had pretty good feel for his split. He threw a lot of them. Early in the game, I thought he had a pretty decent breaking ball, and then execution got a little bit spotty as the game went along."

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The positive: Mize — the 2018 No. 1 overall pick — showcased a dominant splitter for the first time in a long time. His slider remains an issue and led to his struggle, but the combination of his high-velocity fastball and nasty splitter mystified the Rockies for four-plus innings.

His 19 splitters generated eight whiffs on 13 swings, a 61.5% whiff rate.

"It was good," Mize said. "Landing it right below the zone, I felt really comfortable doing that. I was throwing it a little bit harder, as well. It was a good pitch for me."

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The improved splitter wasn't happenstance.

His splitter averaged 87.1 mph in his 19th start, up 1.1 mph from the average velocity in his first 18 starts. He purposefully threw his splitter harder than usual to keep the once-revered offspeed pitch over the plate, rather than a slower splitter that too often sails arm-side off the plate.

"If I try to throw it harder, it just comes out of my hand a little bit truer," Mize said. "I feel like I can command it a little bit better. It's something we've been working on. Hopefully, we can keep that rolling."

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Mize, despite the splitter success, surrendered four runs on six hits, including three runs on four hits in the fifth inning before the Tigers pulled him. But he didn't walk any batters, and six of his seven strikeouts were swinging strikeouts.

There was a lot to like.

It was a start he needs to build on.

"Started better than it ended," Mize said, "but I think the important thing is we won. The bullpen picked me up and put up zeros and held that line for us, and we came out with a win. That's what matters."

Contact Evan Petzold at epetzold@freepress.com or follow him @EvanPetzold.

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This article originally appeared on Detroit Free Press: Detroit Tigers RHP Casey Mize takes step forward with splitter