Lefty Coulombe emerging

ARLINGTON, Texas — Not all is wrong in Oakland’s bullpen, despite some recent lapses. The A’s have some strong performers, too, and none perhaps has been more important than left-hander Daniel Coulombe. Coulombe flies a little under the radar, but with Sean Doolittle out for an unknown time with a shoulder injury, Coulombe is the lone lefty, and he has been faring well. He came into Saturday’s game in the eighth with men at the corners and two outs and got ShinSoo Choo to ground out. Coulombe is holding lefties to a .136 average after entering Sunday’s game in the eighth and striking out Joey Gallo.

Opponents are 1-for-17 against him with runners in scoring position, putting him among the top five in the AL.

“It’s a different role for him now, more of a matchup-type thing,” manager Bob Melvin said. “Maybe we have to start moving him in there a little more so . ... He hasn’t been in that role before; not only does he have to get comfortable with it, I have to be comfortable with it. When he goes in and does what he did (Saturday) night ... it makes you that much more confident.”

Coulombe might get used quite a bit at Seattle this week, especially if left-handed-hitting Robinson Cano or Kyle Seager is up in a big situation late.

Oakland’s bullpen has allowed 10 runs in the past three games and has blown six of 14 save opportunities, but the team could get a key reliever back this week: Melvin said setup man John Axford ,on the disabled list all season with a shoulder injury, might need only one more rehab outing.

Melvin said it’s possible that if all continues to go well, Axford could come off the DL on the next homestand, which begins Thursday.

Briefly: The Chronicle has learned that catcher Bruce

Maxwell was optioned to Nashville to make room for Monday starter Sean Manaea to come off the DL. … In addition, left-hander Ross Detwiler, who had a 1.17 ERA in May with Nashville, opted out of his deal, according to a source, and was granted his release . ... Nashville outfielder

Andrew Lambo was released.