Flushing, NY – Ryan Zimmerman singled in the go-ahead run in 2, in the second game series.
"I'm pleased with what I'm seeing [with Wang]. ... He's giving us a chance to win," Nationals manager Davey Johnson said.
Dillon Gee lasted 5 2/3 frames and was charged with two runs on six hits for New York, which has dropped four straight.
Tuesday was Star Wars night at Citi Field, but the outcome seemed like a rerun of a bad movie for the Mets, who gave up the go-ahead run in the seventh frame for the second straight night.
Stammen, after stranding runners on second and third in the sixth, singled off Dale Thayer (0-2) with one out and eventually scored on Zimmerman's single through the left side of the infield.
Lucas Duda, looking for his second career four-hit game, swung at strike three in the dirt to end the rally and finish off Drew Storen's 36th save.
The Mets broke a scoreless tie in the fifth when Duda's single allowed Reyes and Tejada to score, the latter sliding in safely after Jayson Werth kicked the ball around in right field.
Ankiel, who threw out Josh Thole at home plate prior to Duda's hit, doubled in a run in the sixth and later scored on Morse's two-bagger to tie it.
"I let myself get more rushed every pitch. I sped myself up," Gee said of the sixth.
Reyes reached base four times on three hits and one walk...The Mets stranded 10 runners...The season series is tied, 8-8, with two to play.