"This move gives us two young, polished pitchers who immediately bolster our starting pitching depth, while adding to our roster flexibility," Dipoto said.
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The Mariners are looking for rotation depth after dealing right-hander Taijuan Walker to the D-backs as part of a five-player swap last week that brought shortstop Jean Segura to Seattle. The club has five returning starters in Felix Hernandez, Hisashi Iwakuma, James Paxton, Ariel Miranda and Nathan Karns, but Whalen and Povse add to the pool.
Povse was the Braves' No. 20 prospect, per MLBPipeline.com, while Whalen was ranked 22nd. Jackson was Seattle's No. 6 prospect.
Whalen, 22, was 1-2 with a 6.57 ERA in five starts with the Braves last season before going on the 15-day disabled list in late August with right shoulder fatigue. He began the season with Double-A Mississippi, going 7-5 with a 2.49 ERA to go with 94 strikeouts and 37 walks in 101 1/3 innings over 18 starts.
Whalen was promoted to Triple-A Gwinnett on July 14 and was 0-1 with a 1.93 ERA and 18 strikeouts over 18 2/3 innings in three starts before being promoted to the Majors. Whalen was a 12th round selection by the Mets in the 2012 Draft out of high school in Florida.
Povse, 23, was 9-6 with a 3.36 ERA in 26 starts between Class A Advanced Carolina and Mississippi. The 6-foot-8, 250-pounder had 13 strikeouts and 29 walks in 158 innings. He wrapped up his season by going 4-1 with 2.93 ERA in 11 starts at Double-A. He was selected by the Braves in the third round of the 2014 Draft out of North Carolina-Greensboro.
In Jackson, the Mariners gave up a player selected with the sixth overall pick in the 2014 Draft out of Rancho Bernardo High in San Diego. The 20-year-old hit .243 with 11 homers and 55 RBIs in 92 games for Class A Clinton last year. In three seasons in the Minors, Jackson batted .233 with 21 homers and 109 RBIs in 191 games.
Jackson was a catcher in high school, but the Mariners converted him to the outfield as soon as he signed in 2014.
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.