A year after trading for a first-overall pick in Dansby Swanson, the Braves picked up another first-rounder.
The Mariners traded Alex Jackson and a player to be named later for right-handed prospects Max Povse and Rob Whalen on Monday.
"This move gives us two young, polished pitchers who immediately bolster our starting pitching depth, while adding to our roster flexibility," Mariners' executive vice president and general manager of baseball operations Jerry Dipoto told MLB.com.
Jackson, who was Seattle's No. 6 prospect at the time of the trade, just finished his third pro season with Class A Clinton. The 2014 sixth overall pick hit .243 with 11 homers and 55 RBIs in 92 games. Predominantly a right fielder, Jackson made just two errors all season.
With an above-average fastball, Povse sported a 9-6 record and a 3.36 ERA with 139 strikeouts and 29 walks in 158 innings spanning 26 starts for Class A Advanced Carolina and Double-A Mississippi. After three seasons in the Minors, the 23-year-old was Atlanta's No. 20 prospect at the time of the trade, but bumped up to No. 10 on the updated Seattle list.
Whalen, the former No. 22 Braves prospect who is now No. 14 with the Mariners, had a breakout 2016 campaign. The 22-year-old went 7-6 with an organization-leading 2.40 ERA with 112 strikeouts and 44 walks in 120 innings across 21 starts between Mississippi and Triple-A Gwinnett.
Whalen made five starts in the Majors before hitting the disabled list with right shoulder fatigue on Aug. 25. After switching to the 60-day DL, the Braves activated the 2012 Draft pick on Nov. 4.