Think Muhammad Ali near the end of his legendary career getting pummeled by Larry Holmes, and there you have the sad spectacle Johan Santana has become.

For the sake of Santana's dignity, the Mets might want to finally tell their former ace to go home for the year and see if six months of resting his surgically repaired left shoulder can somehow resurrect him for 2013.

Last night, Santana dominated early and then turned into a punching bag in the middle innings, sending the Mets to a 6-4 loss to the Nationals in front of 34,827 at Nationals Park.

"My season has been a roller coaster," Santana said after allowing six earned runs on seven hits over five innings for his fifth straight loss.

For the second time in less than a week, Santana wouldn't rule out the possibility of a shutdown.

"The next outing, we'll see what the situation will be," Santana said. "Right now I feel fine. I've done everything we were supposed to do and even better than what a lot of people thought I was going to do this year, but at the same time we're competing and I want to win.

"I want to help and go as deep as I can in the game. We'll see the next couple of days what [team officials] have to say and what we're going to do."

Santana (6-9) became the first pitcher in franchise history to allow at least six runs in five consecutive starts, losing each one with a combined 15.63 ERA. He has allowed eight home runs over that stretch, punctuated last night by Michael Morse's grand slam and Bryce Harper's two-run homer.