ST. LOUIS -- When a sinkerball pitcher earns 17 outs via grounders, odds are he probably had a good game.

Mike Leake certainly did Friday night, snapping a six-start streak without a win as he worked eight strong innings in the St. Louis Cardinals' 8-1 rout of the Washington Nationals at Busch Stadium.

In upping his record to 6-6, Leake gave up five hits and a run, walking three and striking out four. He induced four double-play balls and threw just 93 pitches in his first victory since May 24 at the Los Angeles Dodgers.

"Going into the game, you know you're going to get ground balls," St. Louis shortstop Paul DeJong said. "You've got to make plays. We're trying to help out our pitcher and the double plays helped."

Although Washington (47-33) managed eight baserunners against him, Leake faced just three batters over the minimum. He also helped his cause by picking Michael Taylor off first before Bryce Harper could bat in the third inning of a scoreless game.

Nationals manager Dusty Baker, who managed Leake for the first four years of his career in Cincinnati, wasn't surprised by his performance.

"I hate to face a pitcher that's one game under .500 because they always pitch their best to get back to .500," Baker said. "He's a good pitcher. I had him and he knows how to pitch."

While Leake cruised, Washington starter Tanner Roark struggled again, undone this time by an utter inability to make acquaintance with the strike zone. Roark (6-6) walked a career-high five and threw a whopping 85 pitches in three innings, giving up four hits and three runs while fanning two.

Roark made it through the first two innings despite three walks, but leadoff passes to Tommy Pham and Stephen Piscotty in the third finally led to trouble. After Jedd Gyorko's infield hit filled the bases, Yadier Molina grounded a two-run single up the middle.

Two outs later, Greg Garcia added an RBI single to left-center for a 3-0 advantage.

"Falling behind every single hitter was the source of everything," Roark said. "My fastball command, which is my bread and butter, just wasn't there tonight. Five walks is never, ever good."

So bad, in fact, that Roark was pulled before the bottom of the fourth for reliever Jacob Turner. St. Louis pounced on him for five quick runs to end any suspense before the game was official.

Gyorko rifled a ground-rule double to right-center that scored Matt Carpenter. Molina drilled another two-run single through a drawn-in infield. DeJong capped the outburst with his sixth homer, a 426-foot blast to the seats in left-center.

"I felt like it was a matter of time," Cardinals manager Mike Matheny said of his offense. "We were grinding out competitive at-bats, making (Roark) work real hard. It was one good at-bat after another."

Pham, Gyorko, Molina and Garcia each finished with two hits in St. Louis' 11-hit attack. It was the third straight win for the Cardinals (38-41), who have captured five of their last six games and remain 3 1/2 games behind first-place Milwaukee in the National League Central.

Matheny has maintained as his team has struggled to find any kind of traction since mid-May that it was capable of playing crisp, clean baseball. While six games is clearly a small sample size, he's seen enough to believe St. Louis is over a 12-25 skid that left it at seven games under .500 less than a week ago.

"It's great to talk about it," he said, "but now you're seeing all the components. We hit some ruts and it put some doubt in everyone, but playing like this gives you an extra bit of confidence. It sets the tempo for what it needs to be going forward."

NOTES: St. Louis announced Friday that general manager John Mozeliak is being promoted to president of baseball operations. Michael Girsch is the new GM and vice-president. Both signed contracts through 2020. ... Cardinals LHP Zach Duke (left elbow surgery) started a rehab assignment Friday at the team's Gulf Coast League affiliate, pitching an inning and allowing a hit while fanning one. ... Washington officially put SS Trea Turner (broken wrist) on the 10-day DL and recalled INF Adrian Sanchez from Triple-A Syracuse. The Nationals also transferred LHP Sammy Solis (left elbow inflammation), currently on a rehab stint at Syracuse, to the 60-day DL.