WASHINGTON -- Jon Rauch, who reported tenderness in his right elbow Monday, will remain active but will not be with the team during a three-game series that opens Tuesday night in D.C., Terry Collins said.

Team doctors discovered "debris" in Rauch's pitching elbow, Collins said, although the manager was unsure whether the precise issue was bone chips or something else. Collins said medical officials believed the elbow discomfort would calm with three days of rest and Rauch would be available for the weekend series against the Yankees in the Bronx.

So in order to create roster room for the additions of Chris Young and Miguel Batista, the Mets placed right-handed reliever Ramon Ramirez on the DL and designated Jack Egbert for assignment. The latter move exposes Egbert to waivers, but frees a 40-man roster spot for Young.

Ramirez injured his hamstring racing in from the bullpen to celebrate Johan Santana's no-hitter Friday.

"Not in the celebration -- running to the celebration," Collins said. "He was so excited, he burst out of the bullpen."

Collins said Bobby Parnell will serve as the primary set-up man to closer Frank Francisco this series. The Mets really will have only a five-man bullpen this series, since they are going with a six-man rotation this turn in order to accommodate extra rest for Santana and to not use R.A. Dickey on short rest.

Santana, now due to pitch Friday in the Bronx, threw his between-starts bullpen session Tuesday afternoon at Nationals Park. Afterward, Santana reported the session went fine.

Young likely will be capped at 85-90 pitches Tuesday night, in his first major league start since shoulder surgery on May 16, 2011.

Collins during spring training had floated the Mets using a six-man rotation for a chunk of the season once Young returned. But the manager no longer plans to have more than a five-man rotation once Santana is recovered from the no-hitter and 134-pitch aftereffects.

Since the spring-training declaration of potentially a six-man rotation, Mike Pelfrey has been lost to Tommy John surgery, thinning the available starting candidates. And Collins added that Dickey is pitching too well to not be used every fifth game.

Collins said one recent discussion involved letting Dickey go every fifth game, while still having a six-man rotation -- meaning other starters might be pitching on extra days of rest to work around the knuckleballer's schedule. But that discussion has been tabled.

• The Mets announced the minor surgical heart procedure Jon Niese predicted he would likely undergo during the All-Star break -- known as "ablation" -- is more likely to be performed during the offseason. Niese requires the procedure to address an occasionally irregular heartbeat. Niese next is due to pitch Sunday in the Bronx.

• Jason Bay (fractured rib) is due to play a rehab game tonight in the outfield for Class A St. Lucie, a day after being scratched because he was ill. Collins said he was not yet sure whether Bay would be activated from the DL on Wednesday.