The additions aren't surprising, starting with Barreto, the club's No. 1 overall prospect on MLBPipeline.com who, at just 20 years old, is considered close to Major League-ready after concluding his season with Nashville.
Barreto batted .281 with 10 homers and 50 RBIs in 119 games for Double-A Midland. He played four games with Nashville after getting promoted on Aug. 31.
Brugman, who can play all three outfield positions, opened eyes this year with an exceptional showing with Nashville following his midseason promotion, batting .295/.352/.438 with 67 RBIs in 94 games.
Among dozens of players in the A's system left available for the Rule 5 Draft are right-hander Dylan Covey, the club's No. 20 prospect who missed most of 2016 with an oblique injury, and right-hander Tucker Healy, who racked up 76 strikeouts in 52 1/3 innings in Triple-A this year.
MLB requires teams to add players who signed at age 18 or younger to 40-man rosters within five professional seasons, or those who signed at 19 or older within four seasons, or they will become eligible for other organizations to draft. Clubs pay $50,000 to select a player in the Major League phase of the Rule 5 Draft, slated for Dec. 8. If that player doesn't stay on the 25-man roster for the full season, he must be offered back to his former team for $25,000.
Jane Lee has covered the A's for MLB.com since 2010. Follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.