Nuno, a reliever and spot starter for the Mariners this season after being acquired from Arizona in early June, gave up a two-out single to Prince Fielder in the first inning, but completed the next six without giving up another hit. A powerful lefty, Nuno fanned 10, walked two and hit a batter.
Meanwhile, Seager and Trumbo both delivered two-run homers, Trumbo's in the third and Seager's coming in the fifth inning. All six other hits by the pair were singles.
After Kelly Johnson's solo homer tied the game at two in the top of the eighth, Stephen Strasberg fanned Kurt Neiwenhaus for his 13th strikeout and then allowed a one out single to Curtis Granderson. Relieved by Drew Storen, Strasberg saw his chance for a win vanish on one swing by he next batter, Yoenis Cespedes, who launched a two-run homer over the wall in left center.
A one man wrecking crew for the Mets over the past seven games (.424, 5 HR, 11 RBI), Cespedes victimized the Nationals during the three-game series in Washington, going 6-for-14 with two homers and seven RBI.
With the sweep, the Mets have a seven-game lead in the NL East with 23 games to play, a nearly insurmountable edifice to the Nats, who will surely finish in second place in the division (Miami is 19 1/2 back) but will not qualify for the playoffs. The Chicago Cubs have a 9 1/2 game lead on them for the final wild card spot.
The Mets are 5-3 in September and headed to Atlanta for a four-game series with the Braves beginning Thursday. The Braves have the second-worst record in the league, at 56-84.