SEATTLE -- With Spring Training's arrival, an overriding question figures to be asked over and over this season of the Mariners: If last year was the step back, is this team ready now to take the next step?

Clearly, 2020 is the season that youth is indeed being served in Seattle, but how long will it be until this group is ready to contend?

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The practice fields at the Mariners’ Peoria Sports Complex in Peoria, Ariz., are teeming with talented young prospects. Fans will be able to see the much-anticipated outfield duo of Julio Rodriguez and Jarred Kelenic. The initial rotation plans already include rookies Justus Sheffield and Justin Dunn, while 2018 first-round Draft pick Logan Gilbert will also be in big league camp with a flock of other youngsters.

They’ll be throwing at times to big Cal Raleigh, the fast-rising catcher out of Florida State and one of 17 of the Mariners’ Top 30 MLB Pipeline prospects who’ll be in camp.

Around the infield, rookie Evan White is already penciled in at first base even though he’s never taken a swing in a Major League game and was playing at Double-A Arkansas last season. Shed Long Jr., with 42 games of MLB experience, figures to be the second baseman. His partner up the middle is shortstop J.P. Crawford, who is entering his first full season as a starter.

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And while Kelenic and Rodriguez will draw much of the attention as they arrive for their first big league camps at ages 20 and 19, respectively, it’ll be rookies Kyle Lewis, Jake Fraley, Braden Bishop and the just-claimed Jose Siri competing for the starting corner outfield spots this spring.

A Mariners club that featured the oldest lineup in the Majors just two years ago now will have just one player -- 32-year-old Kyle Seager -- who is over 30 in its starting lineup and five-man rotation. Six of the projected nine position starters are 26 or younger. And this is before the rebuild is even complete, with more prospects like the 20-year-old Kelenic and 19-year-old Rodriguez on the way.

"We're super excited," said Dunn, who got his first taste of the Majors with four abbreviated starts last September after a big season for Double-A Arkansas. "We have some really good things brewing here, culture-wise and family-wise, first and foremost. We have some really exciting young players and we love to be around each other and play together. We can't wait to get going."

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It’s a startling transition for a club that was built around 30-somethings Robinson Canó, Nelson Cruz and Félix Hernández in recent years and still had veterans like Seager, Jay Bruce, Edwin Encarnación, Dee Gordon, Wade LeBlanc and Mike Leake playing prominent roles last season.

Only Seager and Gordon are left from that group, and the 31-year-old Gordon is likely to wind up in a backup role to Long and Crawford in the middle infield as the youth movement marches forward.

Mariners general manager Jerry Dipoto has been crystal clear about the team’s new direction, to the point of noting fans shouldn’t expect a postseason contender in 2020. That realistic outlook has rankled some, but Dipoto has always been candid about his plans and he isn’t hiding from the reality of this season’s main objective.

“It’s about the development of our young players,” Dipoto said. “At the end of 2018, we were the oldest team in the American League on the field. And we enter this year, if it all lines up on Opening Day as it sits right now, we're the youngest team in the American League. So we have really shifted a paradigm.

“We have created a great deal of roster and financial flexibility as we move forward. We don't think that we're likely to threaten for a playoff position this year. We will measure our season based on the development of our young players.”

While that approach might be a tough sell for a fan base that has gone 18 years without a postseason appearance, Dipoto believes that he’s undertaken a path to long term sustainable success with greatly increased roster and financial flexibility for the future instead of trying to continue patching together an aging and expensive roster that was at best competing for AL Wild Card berths in an ever-shortening window of opportunity.

Mariners manager Scott Servais was the Rangers' director of player development from 2006-11 when they rebuilt a club that went to the World Series his final two seasons there. As he prepares for his fifth season leading the Mariners, Servais is fully behind the Mariners' youth movement.

While many managers would chafe at the reality of leading a team that is likely to mar their win-loss record, Servais insists that this will be a fun club to watch and work with as the youngsters get their chance to shine.

“They're all trying to prove themselves,” Servais said. “They’re hungry and anxious to get on with their careers. This is what they've been waiting for their whole life, to get an opportunity at the Major League level, where somebody's going to let them play and see how good they can really be against the best in the world.

“I'm looking forward to it. People say, ‘You're crazy. You guys are so young.’ There are going to be some struggles. It's baseball. You never know what could happen. But we will get better throughout the year.”

Servais says that the Mariners will be much improved defensively and on the basepaths with the young and athletic group. Clearly, the pitching prospects have much to prove, and it remains to be seen how youngsters like White, Long, Lewis and Fraley hold up as rookies against MLB pitching on a regular basis.

But those are questions that need to get answered. And that, for the Mariners, is what 2020 will be about.