OAKLAND -- While A's manager Bob Melvin put odds of a Sean Manaea return at 50-50 on Thursday afternoon, he awaited word on the prognosis of one of his other ailing starters.
Left-hander Brett Anderson, diagnosed with ulnar nerve irritation in his forearm, was scheduled to meet with team doctors later Thursday to decipher how best to proceed with treatment.
It's unclear if either pitcher will take the mound again this season, leaving the A's in limbo down the stretch as they operate without their ace and eye a postseason run. Manaea, who is dealing with rotator cuff tendinitis in his left shoulder, is taking anti-inflammatory medication, but remains shut down.
"The longer this goes on and the more we hear about what's going on with him and how he feels," Melvin said, "it's going to be tough for him to make it, but I'm not going to say 100 percent sure that he won't be able to."
"It's super frustrating," Manaea said. "I feel like I'm letting everyone down. It really, really sucks that it had to happen now, but there's nothing I can do about it, just try to get healthy and hopefully help the team at the end of the season."
Manaea said the usual soreness he experiences after starts simply wouldn't subside following his last outing, noting, "This was just a little more intense, and it's not like it got any better. I knew that it wasn't right."
Frankie Montas was recalled from Triple-A Nashville on Thursday to start the series opener against Seattle in Manaea's stead, with Daniel Mengden going Saturday in place of Anderson. J.B. Wendelken was also promoted from Triple-A, while reliever Ryan Dull and outfielder Nick Martini were optioned to Nashville.
The A's operated with a two-man bench Thursday, highlighting their need for extra pitching help as they continue a 20-game stretch without an off-day. Martini, who was impressing in the leadoff spot, is expected back at the conclusion of Nashville's season Monday. Rosters expand on Saturday.
However, outfielder Dustin Fowler could join the A's as soon as Friday to bolster the bench, Melvin suggested. Fowler -- hitting exceptionally well with the Sounds following his demotion a month ago -- was pulled from Nashville's game after only one at-bat Thursday.
"It's certainly nothing Nick has done," Melvin said. "He's been a really consistent performer for us, and we'll miss him in the leadoff spot, certainly against right-handed pitching, but we needed to do this today, because we'll be down some guys."
Wendelken had a 1.59 ERA in five relief appearances with Oakland during his first big league stint this year and didn't allow a run across seven innings after being optioned to Triple-A.