OAKLAND -- Liam Hendriks has done a superb job filling in as the A’s closer, but with Blake Treinen returning from injury, don’t expect any type of controversy in the bullpen.

After Treinen was reinstated from the 10-day injured list, A's manager Bob Melvin wanted to first use the right-hander in a low-leverage situation before he returned to save situations. However, Treinen pitched in the 12th inning of Wednesday's 4-3 loss to the Twins, giving up the decisive run on a hit and two walks in one-third of an inning.

Before the game, Melvin said he wouldn't hesitate sending Treinen to the mound in future save situations.

“He’s had a pretty good body of work for us,” Melvin said. “We just want to make sure he’s healthy and gets out there. You can do all the Minor League rehab you want, but it’s different when you get to the big league level."

That body of work includes a 2018 campaign during which Treinen earned his first career All-Star selection and became the first reliever in MLB history to record at least 30 saves (38), 100 strikeouts and a sub-1.00 ERA. His 0.78 ERA was the best among Major League relievers.

Treinen’s 2019 has not been quite as dominant -- he’s 2-3 with 16 saves and a 4.29 ERA in 31 relief appearances -- but he’s gotten the job done when leading for the most part, with only two blown save opportunities.

Hendriks may no longer assume the closer’s role, but he’s earned himself a spot in high-leverage situations with his strong first half that earned him American League Reliever of the Month honors for June.

Hendriks posted a 0.60 ERA over 14 June appearances, collecting 22 strikeouts and only four walks in 15 innings. In 48 2/3 innings this season, Hendriks owns career bests in ERA (1.29) and WHIP (1.05).

“That’s quite a feather,” Melvin said. “He’s come a long way, not only since last year, but also this year from where he started out. Credit to him for hard work and serious conviction in what he’s doing.”

At age 30, Hendriks is enjoying a career year that was catapulted last September when he returned to the A’s after the club designated him for assignment earlier that June.

“There are certain times I’ve escaped doom on the mound, but other times I feel completely in control no matter what happens,” Hendriks said. “My biggest thing is going out there and maintaining my intensity. Sometimes in the past, I’ve taken my foot off the pedal a little bit and gotten burned. This time, it’s just trying to ride this wave as long as I can.”

Hendriks said he’s allowed role changes to affect his performance on the mound in the past. With Treinen back, the right-hander is not worried about what his new role will be. Whenever Melvin calls his name, he’ll be ready to go.

“I’m going to be whatever role they want me to. I’m not going to say no,” Hendriks said. “If they want me to open, I’ll open. Throw the seventh, I’ll throw the seventh. Whatever role, I’ll be ready for it. I’m just happy to be pitching on this team.”

To make room for Treinen on the active roster, Aaron Brooks was designated for assignment. The right-hander earned a spot in the starting rotation out of Spring Training and went 2-3 with a 5.74 ERA in six starts before moving to the bullpen in May. He logged a 3.79 ERA in nine relief appearances and was 2-3 with a 5.01 ERA in 15 games overall.

“He had to acclimate to what was a tough role for him, and I thought he did a pretty good job doing it here recently by eating up some innings in the bullpen,” Melvin said. “ We’d love to have him and stretch him out in Triple-A and get him in a starting role again, because our depth isn’t as deep as we originally envisioned. If that’s the case, great. If not and somebody picks him up in the big leagues, we wish him the best.”

Manaea throws bullpen

Sean Manaea returned to the mound Tuesday for a 30-pitch bullpen session. Working his way back from shoulder surgery, it was the left-hander's first bullpen session after getting shut down for a brief period on June 23 with discomfort on a right side muscle. Manaea will take two days off and throw another 30-pitch session on Friday.

Cotton to throw batting practice

Jharel Cotton will head to Stockton on Thursday to throw 20 pitches of batting practice against the club’s Class A Advanced affiliate. Cotton said he expects to go on a Minor League rehab assignment if all goes well during the session, with August as his target for a return to the big leagues.

The right-hander is returning from Tommy John surgery and will likely pitch out of the bullpen in 2019, before converting back to a starting role next season.