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07/18/12 6:55 PM ET

Rauch has fluid drained from both knees

WASHINGTON -- The Mets signed right-hander Jon Rauch over the winter to pitch in some of their highest-leverage situations. But with Tuesday's game on the line, a right-handed hitter at the plate, and closer Bobby Parnell already in the clubhouse, manager Terry Collins passed over Rauch in favor of Pedro Beato.

Turns out there was a reason. Rauch said he was in "quite a bit of pain" Tuesday due to his knees filling up with fluid, "to the point where I could barely even walk." Around game time, a doctor came to the clubhouse to drain both knees and give Rauch a cortisone injection, which reduced the pain.

Because of the procedure, Collins believed that Rauch was unavailable in the 10th inning Tuesday -- even if Rauch disagreed.

"I could have pitched," Rauch said. "I could have pitched through pain. It wouldn't have been the first time."

Rauch has undergone surgeries to both knees in his career and endured arthritis for years, prompting him to receive an injection of synthetic cartilage on July 8. But he had a bad reaction to the procedure and his knees filled up with fluid, which a doctor drained Tuesday.

Calling it "an oil change," Rauch said he felt significantly better Wednesday and was available to pitch if needed.

Collins chooses Bay for defense in middle game

WASHINGTON -- Despite removing Jason Bay for pinch-hitter Jordany Valdespin in the ninth inning Tuesday, Mets manager Terry Collins passed on an opportunity to take Bay out of his starting lineup the following day. Citing a need for fortified outfield defense with extreme fly-ball pitcher Chris Young on the mound, Collins opted to start Bay over Valdespin in left field.

But that does not mean Bay is an everyday player for the Mets. After missing two large chunks of this season with a fractured left rib and a concussion, Bay must earn his way back into regular playing time.

"I'm going to mix and match a little bit," Collins said of his outfield situation, after speaking to Bay about the subject Wednesday afternoon.

That could mean additional playing time for Valdespin or Kirk Nieuwenhuis, with Bay and Scott Hairston starting regularly at the corner outfield positions against left-handed pitchers. It could also mean a reduction in time for right fielder Lucas Duda, who returned to the lineup Wednesday, two days after receiving a cortisone injection in his strained left hamstring. Duda has scuffled against left-handers this season, slugging just .315 with a .274 on-base percentage.

But Bay nonetheless remains one of the top priorities in that outfield mix, given his potential to fill the Mets' need for a power right-handed bat.

"We've got to get him right," Collins said, while also referencing his other slumping players. "We did it with Ike [Davis] and we got him right. It's the same thing with Lucas right now. Lucas is going through a little bit of a funk, but we know how important his bat is in our lineup. We've got to get him in there and get him started again."

Mets' Francisco likely won't return until August

WASHINGTON -- A July return seems out of the question for injured closer Frank Francisco, who will not restart his Minor League rehabilitation assignment until next Friday.

The plan is for Francisco to throw bullpen sessions next Monday and Wednesday, before appearing in the first of two or three rehab games on July 27. Should all go according to plan, that would put Francisco in line for an early-August return.

The closer has already suffered one setback in his rehab from a strained left oblique, which has sidelined him since June 23.

In Francisco's absence, Bobby Parnell has begun struggling as the team's dedicated closer, blowing two consecutive saves after converting his first two opportunities.

"When you've got that kind of stuff, you've got to make the hitters a little bit more uncomfortable than [Parnell's] made them," manager Terry Collins said, saying he met with Parnell on Wednesday to suggest that he throw inside more often. "Frankie is one of those guys that works both sides of the plate with his fastball. It keeps them a little more off-balanced."

Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDicomo. This story was not subject to the approval of Major League Baseball or its clubs.