Detroit Tigers right-hander Matt Manning, the franchise's 2016 first-round draft pick, isn't dominating in Triple-A Toledo. He shows flashes of success, but the Tigers haven't been able to develop him into a steady starting pitcher they can rely on.

Right now, Manning is working on his delivery with the Mud Hens.

The Tigers have called up right-hander Keider Montero — not Manning — the past two times they've needed a starting pitcher from Toledo, including Wednesday's series finale against the Philadelphia Phillies.

"I think seasons can lead to a lot of these little mini-decisions," manager A.J. Hinch said before Wednesday's 6-2 loss, "and if you're not careful, all of us can assume a lot of different things like, 'Oh, it's going to be this guy, or that guy,' even the quick call-ups. There's a great assumption on what we will probably do, but when you take a step back and look at what's needed, it can go a different way."

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Manning, 26, has a 4.88 ERA with 12 walks and 23 strikeouts across 27⅔ innings in five appearances for the Tigers this season. He also has a 5.68 ERA with 13 walks and 42 strikeouts across 38 innings in eight games for the Mud Hens. At both levels, left-handed hitters hate tagged him for a .304 batting average with an .893 OPS.

He has made his past four starts in Triple-A Toledo.

Manning was rocked in his most recent start Saturday against St. Paul, the Minnesota Twins' Triple-A squad. He threw 88 pitches and allowed eight runs on nine hits and two walks with four strikeouts across four innings, surrendering three home runs.

"Matty is still working on delivery," Hinch said. "He's still working on execution. There are plenty of things that we still want him to do. We also want the guys down in Triple-A to not assume, as well. You gotta give opportunity to guys that you feel good about. It's not just one person because we're used to it. He's still got to earn his way like everybody else."

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Recently, the preferred choice has been Montero.

But Montero — like Manning — has struggled at the Triple-A and MLB levels. The 23-year-old has a 5.03 ERA with 30 walks and 54 strikeouts across 48⅓ innings in 13 games for the Mud Hens. He also has a 9.35 ERA with four walks and 11 strikeouts across 8⅔ innings in two games for the Tigers, after making his MLB debut on May 29.

Facing the Phillies, Montero allowed five runs on five hits and three walks with six strikeouts across 4⅔ innings. He gave up two runs after facing just two batters, the result of a leadoff walk and a two-run home run.

Montero doesn't dominate the strike zone.

"One of his issues as a young pitcher has been losing some of that command, control and spraying the ball quite a bit," Hinch said. "He's got swing-and-miss stuff, which he can rescue himself out of a few innings, and then some he can't. We try to focus on that one pitch at a time mentality, getting him into counts and getting him ready to use his chase stuff."

There are 126 pitchers at the Triple-A level with at least 40 innings. Among the group, Montero ranks 33rd with a 24.1% strikeout rate and 111th with a 13.4% walk rate.

He needs to throw more strikes.

"Pitch sequencing is important for him, incorporating the third-pitch changeup is important," Hinch said. "He's the classic young pitcher who has really good stuff, and he's trying to harness it around the strike zone. The more he does, the more he'll factor in up here."

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 right-hander Matt Manning 'working on delivery'