ANAHEIM -- Frankie Montas has been away from the A’s for three months due to an 80-game suspension following a positive test for a performance-enhancing substance, but he’s fully aware of what he’s walking into.

Montas held a session with reporters in the interview room at Angel Stadium before Tuesday’s 3-2 loss to the Halos, as he's set to return to an Oakland club that finds itself in position to capture a postseason berth for a second consecutive year. The A's hold a slim half-game lead over the Rays for the top American League Wild Card spot, with the Indians trailing by just one game.

From his home in Arizona, Montas kept up with the club religiously, watching every A’s game on television while keeping his arm in shape by throwing on a normal schedule at the team’s Minor League complex in Mesa. The right-hander will officially be reinstated before Wednesday’s game as the starting pitcher for that night. Montas is eligible for Oakland’s final five games of the regular season, as well as any potential one-game playoff in the event of a tiebreaker -- though he'll be unavailable for the postseason.

“I was sad, and at the same time, disappointed, especially for my teammates. The team is my family, and it was a tough situation. But we got out of it,” Montas said. “I’m proud of my teammates. It was a little bit sad because I couldn’t be there giving my support.”

Montas spent some time in the A’s clubhouse on Tuesday afternoon, reunited with teammates who have more than held their own in his absence.

“A lot of these guys have kept in touch with him,” A’s manager Bob Melvin said. “I’m sure it was hard for him watching from afar, as key a piece as he was for us. In the first half of the season, he would have made the All-Star team. It’s probably hard going through that, but I know he’s excited to be back. As far as the clubhouse goes, my guess is they’ll welcome him back.”

Montas' return gives him an opportunity to finish what was looking like a breakout campaign after bouncing around organizations earlier in his career. The 26-year-old right-hander went 9-2 with a 2.70 ERA across 15 starts -- with the A’s going 11-4 in those games -- and his 2.9 WAR at the time of his suspension was fourth best among qualified starters, according to FanGraphs.

“It feels good. It’s been a tough time for me and my family waiting for the suspension to be over. I’m happy to be back with my teammates,” Montas said. “I kept in contact with a lot of the guys, and I’m just happy to be here to help.”

The A’s were 41-36 when Montas was suspended on June 21 and have taken off since by going 53-26 in 79 games during his absence, but there’s no question the club believes it is better with the right-hander part of the mix. Sitting in control of the top AL Wild Card spot, the A’s will look to get a boost from Montas, who recently allowed one run over six innings in a game against the Padres’ instructional league squad last week.

“All of the starters have gone out there and given 100 percent. They did a hell of a job. I’m happy and proud of all of them,” Montas said. “I’m built up pretty good. I’ve been throwing up to 100 pitches down in Arizona, six innings each time. I think I threw about 47 innings down there, so I’m pretty ready right now.”

Trivino and Treinen done for season

If the A’s are going to reach the postseason this year, it’ll come working around what was a tough year for relievers Lou Trivino and Blake Treinen.

Before Tuesday’s game, Melvin revealed that Trivino, who has not pitched since Sept. 14 with an oblique issue, would miss the rest of the season due to a cracked rib, with a potential postseason return unlikely. Treinen, who was already shut down for the year with what the right-hander called a stress reaction in his back, will also miss the rest of the year, including any playoff action.

“Lou’s cracked rib could mean quite some time,” Melvin said. “We’re saying for sure the regular season. He’s going to get a second opinion, but it doesn’t look great. Blake is done, too. He saw a doctor. Not great for him. Blake’s season is over.”

Treinen was supplanted by Liam Hendriks as the A’s closer in June after struggling to hold leads over the first couple of months of the season. He showed flashes of his old self at times over the past few weeks, with scoreless outings in eight of his last 11 appearances, but after a historically successful 2018 campaign, he finished 2019 with a 4.91 ERA in 58 2/3 innings.

Trivino, who was nearly as dominant as Treinen last year as his setup man, also struggled to regain form in his second big league season. He finished with a 5.25 ERA over 60 innings.

“It’s hard. These guys are not only big on the field for us, but also in the clubhouse,” Melvin said. “Over the course of the season, things have to be done differently. We’re able to pick up the slack for what have been injuries and tough years for those guys. My guess is they’ll be back doing their thing next year when healthy. They’re both talented guys.”

Trivino and Treinen are both likely to be placed on the injured list, which would open up two spots on a potential postseason roster for players who were not on the 40-man roster before Sept. 1, like top prospects such as catcher Sean Murphy and pitcher Jesus Luzardo.