Some players are on the verge of stardom; others are entering a crucial phase of their development and still others are getting their first tastes of full-season ball. With the 2015 season approaching, MiLB.com takes a look at the most intriguing prospects from each MLB organization.

Back and healthy: Jacob Wilson, 2B

Last summer, Wilson played himself into the Double-A Texas League in a hurry, but after hitting .305 through 36 games there, two cartilage tears in his left knee sidelined him for the rest of the season. He picked it back up in the Arizona Fall League, where he saw time at three positions on defense. This spring, St. Louis has been having him get work in at shortstop.

"He continues to create more value for himself by being able to do that. He's already established that he can handle second base, and he did a very good job of that," Cardinals director of player development Gary LaRocque said. "[Having him play shortstop] is really about increasing his value so that when the time comes, the Major League club can take advantage of having a guy who can play multiple positions. That's a real positive for him, and for us."

With his knee surgically repaired and the injury behind him, Wilson is ready to move forward in his development.

"He just needs to continue to get quality at-bats. He's a young man who steps in at every level and shows he can hit. He had work to do early at second base, but not about how quick his hands were. His hands were very quick," LaRocque said. "He's had great opportunity to be seen by [Cardinals manager] Mike [Matheny] and the staff [this spring], and we look to increase his value by having him play multiple positions. That's how we've done it with a lot of players, and it works to help guys move faster into the next level."

Breakout prospect: Carson Kelly, C

On the surface, nothing about the offensive numbers from Kelly's first full season suggest his bat is going to take off this year. Playing 98 games for Class A Peoria, he batted .248 with six homers. But consider that Kelly, who turned 20 in July, had spells during which he piled up hits with ease (he had seven hitting streaks of four games or more, and 24 multi-hit games), and consider that it was his first season as a catcher, and it stands to reason it's only a matter of time before he gets the results at the dish he's capable of.

"There are a lot of college juniors who come out of the Draft and hope to do that well in the Midwest League. He went through stretches last year where his defense was just great and stretches where he was really hitting the ball," LaRocque said.

"Now it's just to have him put them together over longer periods of time. That's no surprise, that it came in stretches. Of course! He was 19 years old. That's to be expected."

The Cardinals moved Kelly behind the plate during the fall instructional league of 2013 after selecting him out of an Oregon high school as a third baseman in the second round in the 2012 Draft. It's early still, but the conversion has all the markings of a success.

"He was very comfortable behind the plate very early. He's never been uncomfortable from Day 1 way back in instructs when we started that change," LaRocque said. "He has a great attitude; he loves to work. The defensive part, pitchers, coaches, coaching staffs -- the pitchers say he's very easy to throw to and they like to throw to him, and the staff watches him every day and has great things to say.

"Mike Matheny works very closely with all of our catchers [during Spring Training], and we're grateful for that. With Mike and with Yadi [Molina], Carson just takes it all in."

Given his youth, it'd be something of a surprise to see Kelly reach higher than Class A Advanced Palm Beach this year, but the more experience he gets behind the plate and the more professional at-bat he logs, the better he's going to look.

"To see Carson Kelly make adjustments so quick, and he has a real strong character, a great work ethic…" LaRocque said. "It should play this year."

Best tool: Sam Tuivailala's fastball

There's plenty to like about Tuivailala as an overall package, but it was on the strength of his fastball that he rose from the Florida State League to the National League last year, and it's his fastball that makes him one of the most exciting pitchers in a system with no shortage of good hurlers.

The pitch has reportedly been clocked as high as 102 mph, and Tuivailala regularly throws in the upper-90s. There's more to the fastball than speed, though -- it has serious movement that makes it tough to lock in on even if a hitter is quick enough to catch up to it.

A native of San Mateo, California, Tuivailala was drafted as a high school shortstop in the third round of the 2010 Draft, but he's been electric since he converted to working out of the bullpen in 2012. In his Minor League career, he's piled up 170 strikeouts over 108 1/3 innings. If he can work on keeping his heater down in the zone even more reliably -- and offsetting it with his power curve -- he's likely to help St. Louis later this season.

Major League-ready: Stephen Piscotty, OF

Over the course of three seasons, Piscotty has steadily climbed through the Minors, and he hasn't lost any steam along the way. Last season, he batted .288 with 32 doubles while playing solid defense in the outfield over 136 games for Triple-A Memphis. He came into spring camp intent on driving the ball more this season.

The 24-year-old California swatted nine homers last year, a substantial dip from the 15 he clubbed in 24 fewer games in 2013, but it's clear that the Cardinals aren't concerned about that part of his game.

"For him to continue to develop [power] will also come with time. It's not something from each Minor League level that we felt he had to do as he was moving up," LaRocque said. "He was really getting adjusted to each league's pitching. The next step is to be able to drive the ball more. But I'll tell you, he hits mistakes hard, and he doesn't give away at-bats. We're pleased with the progress he's made."

He's continued to get on base against more advanced pitching, and through 20 Grapefruit League games this year he was hitting a respectable .268.

"He goes to each level -- all the way through Triple-A -- and he establishes himself," LaRocque said. "We've seen progress over the course of time. He's gone into each league and hit right away. That's a good indicator that he adjusts quickly. He knows how to win. The young man plays the game well."

With the Cardinals outfield depth, they may not have a spot for Piscotty right away. If a chance arises, will he be ready to compete in the Majors?

"Yes, we feel he's been making strides to do that," LaRocque said. "He brings offense to table, and clearly he brings defense. There are a lot of ways he can beat a team."

Full-season debutant: Luke Weaver, RHP

The No. 27 overall pick from last year's Draft threw a total of 9 1/3 innings in the Minors last year, getting pushed around in a couple starts for Palm Beach and cruising through four appearances in Rookie ball. He's fresh and ready for a considerable workload increase in his first full season as a pro.

"The good part was last year we monitored his innings, which we do with a lot of players coming from the Draft into the system," said LaRocque.

Weaver has a very strong changeup to complement his decent fastball and developing slider, and the Florida State University product may get another crack at the Class A Advanced level before long. In mid-March, LaRocque did not want to make predictions about the youngster's trajectory for the season.

"I always say it's not where you are in April, it's where you are in June, July and August," he said. "He's a very good competitor, and he's had success at every level along the way."

Besides, the Cardinals' expectations of Weaver for 2015 don't have as much to do with specific results as with getting acclimated to pro ball.

"What we're looking for is a full season of steady work, to get him through the season and to understand the grind of the day-to-day of the full season as a starter in the Minor Leagues," LaRocque said. "Everybody has to learn that."

More to keep an eye on: Righty Alex Reyes and lefty Rob Kaminsky established themselves as top pitching prospects with dominating performances for Class A Peoria last year. They're each just 20 years old and should be thrilling to watch in the Florida State League. ... LaRocque said of 19-year-old righty Jack Flaherty, the 34th overall pick of last year's Draft, "There's no doubt in my mind that Jack will do the work and get to Peoria, whether it's right away or it's little later on." ... Outfielder Magneuris Sierra, who turns 19 on April 7, raked in the Gulf Coast League last year, hitting .386/.434/.505. Even if he stays in extended spring training during the cold weather weeks, he'll make noise this season.