MLB.com's No. 13 prospect was named Seattle's No. 5 starter by manager Eric Wedge on Monday.

"It was wide open coming in," Wedge told MLB.com. "You saw what I saw, a guy that was very consistent and kept getting better. And as we lengthened him out, he handled that very well. There were situations we thought he handled very well that he'll have to go through in the course of the regular season. All that enters into it."

The 6-foot-7 native of the Dominican Republic made the Mariners' decision easy with an excellent spring. Pineda posted a 2.12 ERA in five Cactus League appearances, fanning 15 batters over 17 innings while allowing 20 baserunners. Pineda probably will make his Major League debut on April 5 in Texas.

Pineda was 11-4 with a 3.36 ERA in 25 starts between Double-A West Tenn and Triple-A Tacoma in 2010. His 9.95 strikeouts per nine innings pitched ratio was good for eighth among Minor Leaguers with 130 frames. Pineda tossed a career-high 139 1/3 innings in the Minors last year, something that Wedge is aware of as he attempts to manage the 22-year-old carefully.

"Any young pitcher, you have to keep a close eye on," Wedge told MLB.com. "But he's big, he's strong, he's built up. Obviously no different than anybody else, we'll work off of him."