It was the Rockies' fifth straight victory over the Nationals, who committed three errors in the game that led to three unearned runs.
Julian Tavarez (3-7) issued consecutive one-out walks to Carlos Gonzalez and pinch-hitter Seth Smith in the eighth. Joe Beimel relieved and induced a comebacker from pinch-hitter Ryan Spilborghs but he missed shortstop Cristian Guzman going for the force at second, throwing past the bag to second baseman Willie Harris, who was on the edge of the infield.
"I messed up and threw it to the wrong guy," Beimel said. "I did everything right up until that point. I got the ball I wanted, anticipated the grounder, got it -- and just blew it. There's no other way to describe it."
Barmes followed with the tie-breaking sacrifice fly.
"I was thankful in that situation to get a pitch I could put in the outfield," Barmes said. "That's really all I was trying to do. It worked out."
According to STATS LLC, it was the first time a pitcher had gotten a win without throwing a pitch since Baltimore's B.J Ryan also had a pickoff against Detroit on May 1, 2003.
"It was a very interesting night for me, kind of humorous in a way because I've played for a long time and never seen anything like that," said the 39-year-old Embree.
He credited Rockies manager Jim Tracy, who teamed with bench coach Tom Runnels to call for the pickoff play.
"He's very in tune with the running game. He has good instincts," Embree said.
Huston Street got three outs for his 21st save in 22 chances.
But the Nationals couldn't hold the lead for Jordan Zimmerman, the second of three rookies starting in succession during the series against the Rockies.
Chris Ianetta's sacrifice fly started the Rockies' three-run fourth. An error by second baseman Harris -- he bobbled Dexter Fowler's two-out grounder with runners on second and third -- opened the door to two unearned runs, allowing the Rockies to tie the game at 4-4.
- RHP Jesus Colome, designated for assignment by the Nationals last Saturday, has opted instead for free agency, a team spokesman said Tuesday.
- Colorado RHP Manny Corpas left for Salt Lake City on Tuesday to begin a rehab assignment with Triple-A Colorado Springs. Corpas will pitch one inning Wednesday out of the bullpen.
- The Nationals, who have committed 77 errors, went into the game with the second-worst fielding percentage (.976) in the NL.
- The Rockies' 44 wins are the most before the All-Star break since 2007, when they finished the midpoint at 44-44.