ATLANTA -- Brandon McCarthy has decided to retire at the conclusion of this season. But before calling it quits, the veteran hurler will spend the next couple of weeks evaluating whether his bothersome right knee will be receptive to the mechanical adjustments he has made in an attempt to possibly boost Atlanta's bullpen during the season's final month.

"I'm done after this," said McCarthy, who is 6-3 with a 4.92 ERA in 15 starts this season. "This is it. The offseason is the rest of my life. If I was going to keep playing, a month and a half ago I would have had the surgery that cleans the [knee] and I'd be back next year just a little bit after Spring [Training]."

Having been sidelined with right knee tendinitis since the end of June, McCarthy has long known his days as a starting pitcher are done. But before concluding his 13-year Major League career, he wants to at least try to prove he is physically capable of providing the Braves some relief innings as they fight for a postseason spot.

With Mike Soroka sidelined for the remainder of the season and uncertainty surrounding Luiz Gohara 's left shoulder, the Braves could benefit from carrying McCarthy as a long-relief option once the rosters expand in September. But before committing to this possibility, the team will evaluate how the veteran hurler fares with Triple-A Gwinnett over the next couple of weeks.

"If I go out there and just [look mediocre], then there is no reason to activate me because it just cost someone else a roster spot," McCarthy said. "If I'm not getting outs, what's the point of doing that for a month? But if I feel like I can go out and be good and take up innings, then it absolutely makes sense."

Initially, McCarthy was somewhat pessimistic about his ability to be effective after quickly making the mechanical adjustments necessary for him to overcome his knee ailment. But after throwing a little more than 40 pitches on SunTrust Park's mound late Tuesday afternoon, he was encouraged by how quickly he has found some comfort.

To lessen the strain on his knee, the 35-year-old right-hander has lowered his arm slot and essentially locked his right knee while making a less aggressive separation from the rubber.

"It felt awkward at first, but now it doesn't feel awkward," McCarthy said. "There's no more load in the back. It's like I ride down the mound as long as I can and then just throw it. It's a lower arm slot, so it's easier to get to. So it doesn't feel like I threw before, but it's not crazy different."

Odds and ends

• Right-handed reliever Peter Moylan and McCarthy will both start working out with Gwinnett on Wednesday and then possibly begin throwing in games next week. There's a chance Moylan could return earlier, but for now, he's also scheduled to be rejoin Atlanta's bullpen after rosters expand in September.

• Left-handed reliever Sam Freeman's rehab assignment was transferred to Gwinnett on Tuesday. If his shoulder cooperates over the next week and he is effective, there's a chance he could rejoin Atlanta's bullpen before the end of this month.