PEORIA, Ariz. -- After a rainout Saturday, Cactus League play is set to open on Sunday for the Mariners. But we’ve already had 10 days of practice for pitchers and catchers and four days of full-squad workouts, so here are five observations before the games begin:

1. The kids are comfortable
This is a vastly different camp from perhaps any in Mariners history, for one reason. There are very few veterans on the roster, which makes it easy for the large group of promising prospects and heralded rookies to feel free to be themselves and not worry about fitting into a pecking order.

It helps that the two top prospects, and two youngest -- 19-year-old Julio Rodriguez and 20-year-old Jarred Kelenic -- are both very confident, outgoing players with a clear view of their futures.

Additionally, three potential rookie starters -- first baseman Evan White and outfielders Kyle Lewis and Jake Fraley -- all got a taste of the big leagues last year and are extremely mature individuals. (White spent part of September working out with the Mariners, though he was not added to the roster.)

In most camps, one or two such promising youngsters might be the singular focus of attention. But in this scenario, they’ve been able to operate as a group and thus deflect some of the pressure. Rodriguez and Kelenic seem to do everything in tandem, which helps them. In turn, there’s been so much attention on that young duo that White, Lewis and Fraley are flying under the radar a bit considering they’re all destined for big roles as rookies.

• Notes: Cactus League opener scrubbed; new arm in camp

Manager Scott Servais said the environment has helped those youngsters step up early in camp.

“The biggest difference is the willingness of our young players to talk and to ask questions in big group meetings,” Servais said. “Typically the young guy sits in the back. You know the saying, ‘Be seen, not heard.’ Our guys, if they’ve got questions, they fire it out there. It’s been very impressive. It’s been very refreshing. They’re trying to get up to speed and learn as quick as they can.”

2. The dynamic duo indeed could be special
It has been awhile since the Mariners have had bona fide blue-chip prospects, dating to the Ken Griffey Jr.-Alex Rodriguez days. While it’s premature to put Kelenic and Julio Rodriguez at that level, they both carry themselves like budding stars and certainly have looked the part in initial workouts.

Julio Rodriguez is physically impressive as a teenager at 6-foot-4, 225 pounds and has put on some mammoth power displays in batting practice. He tends to launch soaring shots that hang in the air, while the 6-foot, 196-pound Kelenic typically drives the ball hard on more of a line.

The real tests will come now that the games begin, of course, and these two will begin the year in the Minors. But the future isn't far away.

“Certainly, the talent is easy to see,” Servais said. “I think when the quality of the pitching gets better and they have to make adjustments a little bit quicker, those two guys really are into the game. How they think the game, what they’re looking for, the conversations they have among each other, questions they’re asking some of the veteran players are different, because they don’t just want to be good, they want to be great. And quickly.”

3. This club will be more athletic
It will take time for this young group to mature enough to start winning regularly, but some things should be evident fairly quickly. This year’s team will be more athletic, which should translate into better defense and baserunning.

White and Lewis have filled out impressively, and both look like big leaguers. Both run well for guys their size. Fraley isn’t big, but he’s an excellent runner, and the combination of Mallex Smith, Lewis and Fraley in the outfield should cover some ground.

White is the best defensive first baseman the Mariners have seen since John Olerud in the early 2000s, and the infield will be much better this year with him at first and J.P. Crawford and Kyle Seager on the left side of the diamond from the start. Add in the upgrade behind the plate with Tom Murphy and Austin Nola in place of Omar Narváez, and the defense looks much improved.

As for on the bases, Smith led the Majors in stolen bases last year and the lineup will be more balanced this year with White, Lewis, Fraley and Crawford all capable of running.

4. Don’t ask about the rotation yet
It’s just way too early to make any real projections about a rotation that features a lot of question marks and not much depth. Other than Marco Gonzales, the starting staff is populated with youngsters who haven’t proven anything or veterans coming off injuries.

Even though he’s 28, Yusei Kikuchi has to be included among the youngsters still in the proving stage, as the lefty has just one year of Major League experience, and that year didn’t go well in the second half. There have been positive signs this spring, but let’s see how it plays out once the games begin.

That holds true for rookies Justus Sheffield and Justin Dunn. Both have promising upside, but limited Major League experience. It’s easy to see why 6-foot-6 Logan Gilbert is regarded by scouts as having the most upside of any of the prospects, but he’s destined to start the year at Double-A.

That’s where the future lies, but this year’s success will depend more on the ability of Kendall Graveman and Taijuan Walker to bounce back from two-year injury absences. Both have looked decent in their early throwing, but again the proof will be in their ability to handle the workload of a 162-game season.

It’s possible we could see Dunn make the initial roster as a reliever and be allowed to work in piggyback tandem with Graveman or Walker, since neither will be throwing six to seven innings out of the gate.

5. Spin the wheel on the bullpen
The Mariners have a slew of relievers who could make the 26-man roster. None of them will be big names, but they do appear to have some quality arms and guys just waiting for the opportunity.

The safe bet is that the group that starts the season won’t look anything like the group that finishes the year and this bullpen will be sorted out in trial-by-fire fashion. Two veteran free-agent acquisitions -- Yoshihisa Hirano and Carl Edwards Jr. -- will help fill late-inning roles, but the real story figures to be how soon and which of the flock of promising youngsters that includes Joey Gerber, Sam Delaplane, Yohan Ramirez, Art Warren, Aaron Fletcher, Wyatt Mills and Anthony Misiewicz step up.

Ramirez, a Rule 5 pickup from the Astros, has electric stuff and has been the buzz of the early camp, but he’ll need to show he can throw strikes, which has been his bugaboo all along. Gerber, 22, is a big kid with a mid-90s fastball who could make the jump from Double-A.

Bottom line, on a team with no reliever with more than five career Major League saves, there are going to be some surprising additions before long and the relievers will have the chance to make names for themselves in a hurry.