The Braves added another recent first-round pick Monday when they traded minor league pitchers Rob Whalen and Max Povse to the Seattle Mariners for outfield prospect Alex Jackson, who turns 21 on Christmas Day and might possibly get a fresh start as a catcher.

The Braves will also get a player to be named later as part of the trade.

Jackson, who caught in high school, was the sixth overall selection in the 2014 draft and was rated as high as the 20th-best prospect in baseball before the 2015 season by Baseball America.

After slipping in the prospect rankings following a difficult season at two Single-A levels in 2015, Jackson hit .243 with 32 extra-base hits (11 home runs), 55 RBIs and a .332 on-base percentage and .740 OPS in 2016 for the Mariners’ Single-A Clinton affiliate in the Midwest League.

“We value upside as we believe Alex has a lot of it,” Braves general manager John Coppolella said. “We believe in the potential and the person, and we are excited for his future with our organization.

A three-time prep All-American out of Rancho Bernardo High School in San Diego, Jackson signed with the Mariners for $4.2 million after being the third hitter taken in the 2014 draft. He hit .280 with an .820 OPS in 24 games of rookie ball in 2014, then struggled to with a .207, eight homers and a .683 OPS in his first full season in 2015.

He slipped out of Baseball America’s top 100 prior to the 2016 season and was rated No. 94 by both Baseball Prospectus and MLB.com.

The Braves have looked to add right-handed power and catching depth throughout their organization and will likely give the 6-foot-2, 215-pound Jackson a chance to show what he can do at his old high-school position behind the plate in the spring. The Mariners, meanwhile, got a couple of quality young arms in the deal.

Whalen, 22, made his major league debut in 2016 and went 1-2 with a 6.57 ERA in five big-league starts for Atlanta. He had an impressive 2.40 ERA in 21 starts in the high minors in 2016, including 18 starts in Double-A and three in Triple-A.

Povse, 23, had a solid season in high-Single A and Double-A in 2016, posting a 3.36 ERA in 26 starts with 139 strikeouts and only 29 walks in 158 innings.

Whalen was on the Braves’ 40-man roster, and trading him opened a spot for Sean Rodriguez, the veteran utility player who agreed Thursday to a two-year, $11.5 million contract with the Braves.

In a cruel coincidence, the Mariners opened a spot on their 40-man roster for Whalen by designating for assignment Ryan Weber, the pitcher they had claimed off waivers from the Braves on Nov. 2. Weber could still be retained by the Mariners if he clears waivers.