After Adam LaRoche walked to load the bases, Ian Desmond singled to left field, scoring Anthony Rendon and Werth to make it a 3-1 game.
Bryce Harper then singled to right field to re-load the bases. Asdrubal Cabrera cleared the bases with a double to make it a 6-1 game.
"I'm just trying to get a fly ball and get one in," Cabrera said. "I had a better swing and I cleared the bases."
Cabrera has been comfortable since he joined the Nationals on July 31. Besides hitting in the clutch, Cabrera has a good rapport with his double-play partner, Desmond, and he likes playing in the National League.
"The game is a little quicker, too. I think that's the only difference. The pitchers throw more fastballs, they throw hard," Cabrera said.
Nationals right-hander Stephen Strasburg (10-10) took advantage of the run support, pitching eight innings, allowing one run on three hits and striking out four batters. Like his previous start against the Mets, Strasburg was able pitch on the inside part of the plate and get plenty of outs.
"It opens the plate for him, allows him to throw his other pitches with even more effectiveness," manager Matt Williams said. "But the biggest thing it does, it opens down and away. That's important for him."
Strasburg needed to go deep, as the bullpen was taxed following three straight walk-off wins. The only member of the relief corps who hadn't seen much action lately was left-hander Jerry Blevins, who pitched the ninth inning.
"I guess it's what the doctor ordered," Strasburg said. "I just wanted to go out there and build off the last start and keep doing the things that I've been trying to work on. [Catcher Jose Lobaton] called a great game, we played great defense."
Arizona's only run came in the first inning, when David Peralta homered over the right-field wall, a solo shot that gave Arizona a 1-0 lead. But that was all the scoring the D-backs would do against Strasburg, who set his single-season career high with his 198th strikeout, coming in his final inning.
D-Backs manager Kirk Gibson took notice that Strasburg is no longer the thrower he once saw a few years back.
"He threw the ball [well], obviously," Gibson said. "We got the run in the first inning and he settled right down. We had minimal opportunities off him. He started with his fastball early, his changeup was good tonight, he's got a good breaking ball and he's much more polished than he used to be. He used to be more of a thrower. Now he's got great stuff, electric, and he's certainly grown up to become a good pitcher, as well."
The Nationals scored two more runs in the sixth inning against left-hander Eury De La Rosa. Desmond drove in both runs with a single to right field for a four-RBI night. For the season, Desmond is not hitting for a high average, but he has a team-leading 20 home runs and 77 RBIs. He even stole his 100th career base on Tuesday night.
"It's one of those nights where I didn't hit it super well, but I got some hits," Desmond said. "Fortunately for me, guys were on base in front of me. They have been doing that all year long. I've been trying to do a better job getting on for Bryce [Harper]."
Washington improved its record to a National League-best 71-53 and remained six games ahead of the Braves in the NL East.
"We are feeling good," Desmond said. "We obviously understand there is a lot of work to be done. But there is nothing like playing good, clean baseball."