WASHINGTON -- The Mets came to the nation's capital with questions. They left with answers.

Thursday night's 9-3 win over the Nationals left the Mets not only on top of the National League East, but also confident in the overall stability of their team headed into the last six weeks of the season.

A three-game series against last-place Washington was just the tonic for a team stumbling into Nationals Park on the heels of a ninth-inning loss to Pittsburgh on Monday. The lingering questions of three days ago were answered in spades.

How would the bullpen, shaky of late, hold up? They threw 8 1/3 scoreless innings with nine strikeouts in the series.

How would they perform on the road and against a lesser opponent, the likes of which have given them trouble this year? A three-game sweep -- a first for the Mets on the road this season -- of the Nationals saw the visitors outscore their divisional foe, 25-6.

"If you are to be who you ought to be, you can't come into these games and beat yourself," manager Jerry Manuel said. "You've just got to play good, solid baseball."

And on Thursday, the Mets used a familiar formula to fell the Nationals -- strong starting pitching, an early lead and solid relief work, the same story in all three games in D.C.

The Mets marked the scoreboard first with a pair of runs in the fourth and again in the fifth off Nationals starter Collin Balester. The latter two-spot came in the form of a home run to left-center field off the bat of former Washington catcher Brian Schneider. Two of his three round-trippers this year have come against the Nats.

"I was just running hard, because I don't hit enough home runs, and I didn't know if I'd hit a home run or not," Schneider said with a smile after the game. "It's huge, any time you can add on to a lead."

Balester would last just another inning and allow one more run when Carlos Delgado took him deep in the sixth.

On the visitors' side of the box score, Oliver Perez went 6 2/3 innings and allowed three runs while striking out eight. Between his last outing and Thursday, Perez tied a personal record with 15 consecutive scoreless innings.

Manuel said after the game that Perez's consistency has been important for the Mets recently.

"We just feel very confident when he takes the mound," Manuel said. "He's throwing strikes, velocity is good, he's mixing his pitches. He's just having a tremendous second half."

Perez admitted that he tired late in his start. He allowed all three of his runs with two outs in the seventh, just before leaving the game.

Perez has, in the past, earned a reputation for performing well against good teams, but struggling at times when facing weaker competition. The recent consistency Manuel hinted at, however, is something Perez himself said he's feeling.

"When I'm on the mound, I'm understanding more of the game," said Perez, who boasts a 1.97 ERA in his past nine starts, four of which came against teams that at the time had losing records. "Every game is very important right now. I've just got to keep focused and play baseball."

The Mets added four runs in the ninth against Nationals closer Joel Hanrahan before skipping town to get to Pittsburgh, where they'll play a four-game weekend series.

For Manuel, however, those four runs held plenty of importance.

"We were able to add on [to a lead], which we have not been doing," Manuel said. "I think that's a good sign for us. We did a lot of good things offensively tonight. We moved runners over, got runners in, played really unselfish offensive baseball tonight."

Carlos Beltran summed up the win Thursday -- and perhaps the entire series -- sitting in front of his locker after the game: "Everything went our way."

There was one more positive for the Mets on Thursday night. Roughed up in his last outing, a three-run blown save against the Pirates on Monday that heaped fuel on the fire of talk about the Mets' shaky bullpen, Aaron Heilman came on to throw a scoreless ninth inning, walking one batter and striking one out.

"I thought it was important that he get back out there," Manuel said. "He's a guy that needs to pitch often. He's more effective that way, so it was good to see him get back out there tonight."