The Athletics are set to designate right-hander Aaron Brooks for assignment, Martin Gallegos of MLB.com was first to indicate (Twitter link). His 25-man roster spot will go to closer Blake Treinen, who’s set to return from a short stay on the injured list.

Brooks has been a regular for the A’s pitching staff this season, having amassed 50 1/3 innings in 15 appearances (six starts). However, the results have been underwhelming. Brooks has only managed a 5.01 ERA/5.67 FIP, in part because he has surrendered home runs on 19.4 percent of fly balls. On the other hand, the 29-year-old has logged decent overall strikeout and walk rates (7.69 K/9, 2.5 BB/9) and racked up almost a K per inning as a reliever.

Brooks is in his second stint with the Athletics, who acquired him from the Brewers last September in a minor trade. He was previously a member of the A’s in 2015 when they landed him and Sean Manaea from the Royals in a deal for Ben Zobrist. Brooks didn’t pitch for the A’s that year, though, and wound up going to the Cubs in a February 2016 trade for Chris Coghlan.

In a combined 111 career innings for the A’s, Royals and Cubs, Brooks has notched a 6.65 ERA/5.39 FIP with 6.81 K/9 and 2.68 BB/9.