Peterson, the 12th-overall pick in the 2013 Draft, was Seattle's highest unprotected player as the club's No. 8-rated prospect by MLBPipeline.com, so it's not surprising the Mariners moved him onto the Major League roster rather than risk another team grabbing him in the Rule 5 Draft, which will be held on the final day of the Winter Meetings, Dec. 8, in Washington, D.C.
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The two pitchers were added because both are the types of players teams tend to target in the Rule 5 Draft with the idea they might be able to survive a full-season on a 25-man roster. Fry is a southpaw specialist and Vieira a youngster who was averaging 100-mph with his fastball in the just-concluded Arizona Fall League.
All MLB teams had until 5 p.m. PT on Friday to shield players from the Rule 5 Draft. Those eligible for the Rule 5 process include anyone not on the 40-man roster who signed in 2012 at 18 or younger or in '13 at 19 or older.
Peterson falls into the latter category after being selected in the 2013 MLB Draft out of the University of New Mexico. The 24-year-old posted a .264/.327.455 line with 19 home runs and 78 RBIs in 119 games between Double-A Jackson and Triple-A Tacoma last season, including a .253 average and eight home runs in 46 games at Tacoma before finishing the season on the disabled list with a finger injury.
Mariners general manager Jerry Dipoto said Peterson will come to Spring Training as a first baseman next year and be given a chance to compete, but he will also play the other corner spots some as well.
"D.J. had a real solid bounce-back year," Dipoto said. "Obviously 2015 was disappointing for him. We sent him back to Double-A and challenged him with ways to kick-start his career as a prospect, and he embraced them. We're really encouraged by the progress he made this year and didn't feel exposing him to the Rule 5 Draft would be smart."
Fry is the Mariners' No. 28 prospect, per MLBPipeline.com. Two other prospects in Seattle's top 30 -- infielder Tyler Smith (29) and catcher Tyler Marlette (30) -- were not protected.
Fry, 24, was in Major League camp with the Mariners last spring and figures to be close to MLB-ready after going 3-1 with a 2.78 ERA over 48 appearances with Tacom. He was a 17th-round Draft pick in 2013 out of St. Clair County Community College in Port Huron, Mich.
Vieira, 23, is more of a late bloomer after signing with the Mariners in 2010 as a 17-year-old from Brazil. The hard thrower had control problems -- with 20 walks and 22 strikeouts at Clinton in 2015 when he posted a 6.97 ERA in 31 innings over 22 outings -- until smoothing things out this season in Class A Advanced Bakersfield when he racked up 53 strikeouts with 18 walks while lowering his ERA to 2.84 in 44 1/3 innings with eight saves in 34 games.
Vieira opened more eyes in the AFL in recent weeks when he hit 103 mph at times while allowing four hits and one run with seven strikeouts and one walk in 5 1/3 innings in five games against many of baseball's better prospects.
"Thyago is the surprise popup guy in this," Dipoto said. "This was a huge breakout year for him. Most impressively, just his physical velocity. His velo through the summer was 94-103. I've learned some things in my baseball career and if you have a 23-24 year-old right-hander who who touches 103, there's a reasonable chance he'll be taken in the Rule 5."
Vieira will be given the chance to progress up the Minor League ladder next year after showing what Dipoto called "legit back-end MLB bullpen stuff" in his first fully healthy professional season.