SEATTLE -- When pitchers and catchers report to Mariners' Spring Training in 12 days, none will cast a more imposing figure than 6-foot-5, 247-pound rookie Michael Pineda.

And perhaps none will carry a larger question mark as well, given the high hopes -- and large unknowns -- surrounding the broad-shouldered youngster from the Dominican Republic.

The Mariners would love for Pineda to prove ready for a role in their starting rotation. There is no question of his potential prowess, his powerful fastball, his impressive physique.

At 22, he's the 13th-ranked prospect in all of baseball by MLB.com after dominating at Double-A West Tenn last year (8-1 with a 2.22 ERA) and then showing flashes of brilliance at Triple-A Tacoma, where he finished 3-3 with a 4.76 ERA in 12 starts.

Pineda threw six shutout innings in his Tacoma debut, took a perfect game into the seventh inning at Salt Lake City on July 4 and had 11 strikeouts in five innings of one-hit ball against Sacramento on July 23.

But after missing nearly all of 2009 with an elbow injury, Pineda tired at the end of last season and got rocked in his final few starts before being shelved after throwing 139 innings for the year.

The Mariners thus will be careful with their young prodigy, but they also intend to give him a chance to make the jump to the Major Leagues as soon as he's deemed ready. And Pineda plans to make that clear from the start of camp.

"I always had the dream to someday be here," said the youngster, who grew up among the sugar cane fields of Yaguate in the Dominican province of San Cristobal. "I definitely thank God I have the strength and opportunity to be here at this moment. I'm very excited to have this chance."

Pineda signed as an international free agent with the Mariners in '05 and pitched several seasons in the Dominican Summer League before coming to the United States in '08 to play for Wisconsin in the Class A Midwest League, where he went 8-6 with a 1.95 ERA in 26 games and was the club's Minor League Pitcher of the Year.

The elbow problems limited him to 44 innings with High Desert in the Class A California League in '09 (4-2, 2.84), but an impressive showing in the Mariners' final preseason outing in an exhibition game at San Francisco and his rapid rise through the Double-A and Triple-A ranks last year opened plenty of eyes.

"You're talking about a 6-foot-5, 245-pound guy with a 100 mph fastball as a starting pitcher, which is very rare," Mariners general manager Jack Zduriencik said. "He's young, but he has all the earmarks of a top-of-the-order starter for years to come."

How soon is the question for the Mariners, who will learn a lot more about Pineda's preparation this Spring Training.

"I've seen him throw three times and every time was pretty good," Mariners starter Jason Vargas said. "He's a pretty impressive figure and the ball comes out of his hand pretty nice. I know when he threw in the exhibition game in San Francisco last year, there was a lot of confidence that he presented out there on the mound. That's all you can ask for from a young pitcher.

"He's not going to come here and be the saving grace. He's not going to be Felix [Hernandez] or that huge reliable 250-inning workhorse that he might eventually end up being. He's going to have to take his lumps with everybody else. But the stuff that comes out of his hand and the body he has makes him a durable-looking guy."

Fellow top prospect Dustin Ackley spent time with Pineda in both West Tenn and Tacoma last year and came away impressed with his work ethic and raw talent.

"He's unbelievable," Ackley said. "He's going to be a special player. He's a guy that throws mid-upper 90s consistently and he's got good breaking stuff. I mean, he's just a presence. He's 6-6 or whatever he stands. He's got the body, he's got the look, he's got all the pitches. It's only a matter of time with him."

Pineda ranks his fastball as his No. 1 pitch, followed by a slider and changeup. He says he needs to work on attacking the strike zone and clearly is eager to prove himself at the next level.

"I feel I've got an opportunity to make it," he said, "but I have to work hard and show them who I am."

He'll get that opportunity soon enough as the Mariners' pitchers and catchers gather Feb. 14 in Peoria, Ariz., for their first workout. And when they do, lots of eyes will be on Michael Pineda, the big fellow with the bright future.