NEW YORK -- More reinforcements are on the way for the Mets, whose roster continues to be in flux.

Catcher Josh Thole and reliever Elvin Ramirez will join the Mets in time for Friday's series opener against the Cardinals, the team announced Thursday.

On Friday, in order to make room on the active roster, the club designated right-hander Chris Schwinden for assignment and optioned catcher Rob Johnson to Triple-A Buffalo.

Thole, who had been on the disabled list since May 8 with a concussion, caught all nine innings of Buffalo's game against Columbus on Thursday, finishing 1-for-4 at the plate with a single.

"The timing was there," Thole told the Buffalo News following the game. "That's one thing you worry about. But it's only been 20 days."

Schwinden went 0-1 with a 12.46 ERA in three games, two of them starts. Johnson hit .313 with one RBI in 32 at-bats.

Thole was hitting .284 with one home run in 26 games prior to his injury.

The Mets hope to receive a significant boost from Thole, as well as from Ramirez, who struck out 19 batters and walked one over his last 14 2/3 scoreless innings at Buffalo. A 2010 Rule 5 Draft pick of the Nationals who was later returned to the Mets, Ramirez will give the bullpen a second reliever capable of providing triple-digit heat.

The Mets also announced that reliever Manny Acosta, who was designated for assignment last week, cleared waivers and has been outrighted to Buffalo.