LAKELAND, Fla. — Just before 9 a.m. on Tuesday morning, Casey Mize walked into the Detroit Tigers’ clubhouse.

Mize, an early starter — he usually gets to the ballpark around 7 a.m. — was not late.

But earlier in the morning, his locker inside the Tigers’ major league clubhouse at Joker Marchant Stadium had been cleaned out, the remnants relocated into the far less spacy minor league clubhouse, where he will remain for the rest of the spring.

Mize, the Tigers’ No. 1 overall pick in last year’s MLB Draft — considered by many to be the organization’s top prospect — was one of three roster cuts on this gray and gloomy day, but even in departure, the brightness of his future shone through.

“The kid was awesome,” manager Ron Gardenhire said. “He had a ball. Having him pitch yesterday and seeing him out there was impressive.”

Mize closed his spring with the big club by throwing two innings on Monday afternoon against the Cardinals, cruising through the seventh inning on 11 pitches with two strikeouts before allowing a run on two hits and a walk in the eighth. Given those innings and the schedule — the Tigers are beginning to build up their pitchers’ arms, limiting potential opportunities for youngsters who are not likely to make the team — Mize’s re-assignment to minor-league camp was in the works.

He received official word the next morning, sitting with pitching coach Rick Anderson inside Gardenhire’s office.

The message, Gardenhire said, was this: “I told him, ‘You’re on a great track. You know what you gotta do, you know how to take care of yourself. Continue doing that. Don’t try to throw 98 (mph) if you throw 95 (mph). Just be within yourself.’

“You don’t even have to tell that kid. He’s on a mission. He’s going to push the envelope on our bosses here, because he’s going to be a fast-track guy. He’s got stuff. He’s got major-league stuff right now. The ball, he can make it do a lot of things, so just keep doing what you’re doing.

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“Some guys, when they go down there, you can say, ‘Don’t big league it,’ you know, the whole package. I don’t have to say that to that guy. He’s going to work. He’ll get after it. He’ll get it done.”

Mize will likely start the season at Class A Lakeland, where the Tigers commonly place their highly-regarded prospects to start the season in warmer weather. But given his advanced development, a quick promotion to Double-A Erie could be in order, joining a starting rotation that could include three former first-round picks, along with right-handers Matt Manning and Alex Faedo.

This spring, Mize made three appearances, including the Tigers’ exhibition opener against Southeastern University. In one, he threw just nine pitches before the game was called due to rain.

The 21-year-old righty did nothing to tamper expectations this spring, impressing Tigers coaches — and perhaps, more importantly, his older teammates — with a polished pitch mix, work ethic and attention to detail.

If the team was closer to competing for a postseason appearance, they likely would have given him a longer look. But despite the overwhelming positives, he is not yet ready to pitch in the big leagues yet. Few — if any — are: A couple looks at Mize on the back fields during live batting practice and in limited spring training looks showed enough adrenaline, which will soon be ironed out while pitching full-time in a professional atmosphere.

On a game day as uneventful as any — the Tigers lost to the Blue Jays, 5-2, with many regulars pulled out of the starting lineup because of damp weather and also tough field conditions — Gardenhire’s comments shed a certain light on the team’s rebuilding process.

As he alluded to, the team might not be able to hold Mize back for long. And with him could come Manning, who holds as much potential as any prospect in the organization. With their ascensions could come the keys to turning the process over: Surely, as is customary around baseball, the team will do their best to manipulate their service time clocks, best positioning them for impact when the team is ready to win.

But it would not be a surprise to see both Mize and Manning reach Triple-A Toledo this season, putting them a step away from the big leagues. When that time comes, the Tigers will have no choice but to shift gears, inching much closer to win-now mode than Tuesday, when one of their top prospects was shown the door to get more innings under his belt.

Contact Anthony Fenech at afenech@freepress.com. Follow him on Twitter @anthonyfenech. Read more on the Detroit Tigers and sign up for our Tigers newsletter.