WASHINGTON -- Despite his increasingly puzzling struggles, the outlook for Johan Santana's season remains unchanged -- for now.

Manager Terry Collins met with Santana after the veteran left-hander lost his fifth straight start Friday night, and confirmed that Santana is fully healthy. After throwing three perfect innings against the Nationals, Santana surrendered a grand slam in the fourth and a two-run homer in the fifth, after which his start ended with six runs allowed on seven hits.

However, with the Mets essentially out of the National League playoff picture as they entered Saturday 18 games behind the NL East-leading Nationals and 10 games back in the NL Wild Card race, shutting Santana down for the remainder of the season remains a strong possibility in order to ensure his readiness for next season.

Collins said he wouldn't talk to general manager Sandy Alderson until Monday, when the Mets return home after the Nationals series. But with Santana offering no denial of the notion, his possible shutdown will loom a little longer.

"Well, I don't know if he's asking for it," Collins said. "What he is basically saying is if that's what we think we should do to make sure he's healthy next year, he's on board with it. He understands the whole thought process behind it."

Santana's next start is slated to come Thursday against the Rockies, and the Mets could decide to wait on another outing to see how he throws. With his velocity remaining steady and his command fine for three innings on Friday, Santana's fourth-inning collapse was all the more stunning.

"That's the question we're trying to discover, we don't have an answer to it," Collins said. "When you're trying to get a ball away to Bryce Harper and you leave it down and in, the one spot that he can do damage. Is it mechanical? Is it the release point?

"As far as I'm concerned, it's a baseball issue. Obviously, we will ask for the input of our training staff."

Santana has allowed at least six runs in five consecutive starts, the first pitcher in Mets history to do so. In the process, he has fallen to 6-9 on the year and escalated his ERA to 4.85 while working toward a return to form as the Mets' ace following offseason surgery to repair a torn capsule in his throwing shoulder.

But since his no-hitter on June 1 -- another franchise first -- Santana has collected a loss in seven of his 10 starts, compiling an 8.27 ERA in 49 innings on the mound.

"You know, my season has been a roller coaster, a lot of ups and downs, good days and bad days," Santana said after Friday's start. "But I'm very positive about everything. I'm coming back from a major surgery. ... It means a lot to me, so I look at it in a positive way that this will be a positive sign looking toward the future."

Worth noting

• Prior to the third inning of Friday night's game in Washington, Santana took the mound with a piece of tape over the bright gold Rawlings logo on his black glove. Nats manager Davey Johnson had found the logo distracting and requested it be taped. Neither Santana nor Mets manager Davey Johnson complained about it after the game, a 6-4 Nats win, though Collins was asked about the issue prior to Saturday's game.

"I don't get into talking about other manager's moves, or what they've got to do," he said. "I've got my own problems. I worry about getting some hits right now."

• Since beginning the year 13-5 against NL East opponents, the Mets are 8-20 over their last 28 games against division opponents.

• Kelly Shoppach's seventh-inning home run on Friday was his first National Leauge homer. In his eight-year career, Shoppach's average of one home run every 22.1 at-bats as a catcher is the fourth-highest mark among active players with at least 1,000 at-bats as a backstop.