FORT MYERS, Fla. -- With the Twins having started full-squad workouts on Monday, several top lower-level prospects began their first Major League Spring Training under the developmentally focused system that the front office hoped to implement to a greater extent this offseason and spring.

Here's what Twins director of Minor League operations Jeremy Zoll had to say about four of the Twins' top hitting prospects invited to their first Major League camp this spring, including a pair of lower-level prospects and a pair of quick risers who are nearing the big leagues.

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Royce Lewis, SS (No. 1)

2018 stats: .292/.352/.451, 14 HR, 74 RBIs, 28 steals (Class A/Class A Advanced)

Zoll on Lewis: "We're really proud of the work and improvements he's already accomplished in 2018. I think we're really excited about his offensive game, and it's just a matter of continuing to face better and better competition. On the defensive side, he's made huge strides, but that'll be a larger point of emphasis overall, if we had to pick one."

Looking ahead: According to Zoll, Lewis spent time at the Twins' offseason mini-camps improving the consistency of his throws from shortstop, and the Twins hope to continue to work with him on his accuracy and utilizing his arm strength.

"In terms of range, you'll see him make plays that, you're like, 'That was a big league play,'" Zoll said. "It's pretty exciting when it all comes together."

Alex Kirilloff, OF (No. 2)

2018 stats: .348/.392/.578, 20 HR, 101 RBIs, 44 doubles (Class A/Class A Advanced)

Zoll on Kirilloff: "It's hard to pick out too many flaws in his 2018 season, and we're just going to look to continue to try to push him to continue to build on that."

Looking ahead: Not necessarily in spring, but throughout this season, the Twins hope to expose Kirilloff to first base at the professional level in addition to his play in the outfield. He did not work at first base last season but has high school experience at the position.

"That's something that [manager Rocco Baldelli and bench coach Derek Shelton] are still working through, and I don't know that's necessarily a chief priority for his Major League camp experience," Zoll said. "But we'll see how all of the work group playing time shakes out."

Brent Rooker, 1B/OF (No. 7)

2018 stats: .254/.333/.465, 22 HR, 79 RBIs, 32 doubles (Double-A)

Zoll on Rooker: "With what he did in [Rookie-level] Elizabethton and in the Florida State League as a newly drafted player, we looked to continue to push him aggressively to Double-A this past year. Once he got out of a little bit of a funk in the first month, he really started to take off and it was fun."

Looking ahead: The Twins had planned to send Rooker to the Arizona Fall League this offseason, but a sprained ankle during one of his mini-camps kept the 24-year-old out of action. Zoll has been impressed with Rooker's continued work in the outfield and at first base, and Rooker will work to maintain that defensive versatility to complement his advanced power bat.

"In the call with Brent to let him know we're going to let him go to big league camp, it was, 'Look, you're going to be with [first-base coach] Tommy Watkins and you're going to be with [outfield coordinator] Mike Quade to get better in the outfield. You're going to be working to get better at first base. Not just observing the situation,'" Zoll said.

Luke Raley, OF/1B (No. 19)

2018 stats: .275/.350/.471, 20 HR, 69 RBIs, 19 doubles (Double-A)

Zoll on Raley: "For Luke, he had a really nice year in Double-A. He's firmly on the radar for [Triple-A] Rochester this year, and for him just to get exposed to the big league environment, and work to get him exposed to [hitting coach] James Rowson and [assistant hitting coach] Rudy Hernandez. And let them see what he can do."

Looking ahead: The 24-year-old, who arrived from the Dodgers' organization in last season's Brian Dozier trade, hit 20 homers in 120 Double-A games last season, and the Twins will work with Raley to cut down on strikeouts and utilize his plus power more consistently.

"I think Luke does a really good job of getting to power, but we're going to try to get to that even more regularly by trying to cut down on the strikeouts a tick and give him some tools to utilize the ability he does have in his bat," Zoll said.