MIAMI (AP) When Tanner Roark made an adjustment to stop tipping his pitches, the Miami Marlins quit hitting him as if they knew what was coming.
Roark finally beat the team that kept beating him, pitching 6 2/3 innings Friday night to help the Washington Nationals past Miami 4-1.
Roark (3-3) came into the game 0-3 in three starts versus the Marlins this season with an ERA of 8.40. Against the rest of the majors he's 2-0 in five starts with an ERA of 0.79.
Why the disparity? The Nationals suspect the Marlins spotted a giveaway in Roark's delivery.
''We looked at video,'' he said. ''I would do certain things on certain pitches, so I made an adjustment. The game within the game - it was a minor adjustment, and it worked.''
Before the game, Nationals manager Dusty Baker said Marlins hitting coach Barry Bonds might have noticed a tip-off by Roark. Bonds did such things when he played for Baker in San Francisco.
''Barry is the absolute best at spotting stuff,'' Baker said.
Ryan Zimmerman and Michael Taylor homered to help the Nationals score all their runs in the second inning.
Marcell Ozuna hit his eighth home run for Miami, but Roark had no trouble with slumping slugger Giancarlo Stanton, who finished 0 for 4 with three strikeouts, dropping his average to .214. He has struck out 12 times in the past four games.
''He's a big part of our club,'' manager Don Mattingly said. ''He's going to hit his way out of it.''
Miami has totaled four runs during a three-game losing streak.
Justin Nicolino (2-2) went 5 1/3 innings and has lost all three career starts against Washington. He was hit hard early, but after giving up the two homers retired 10 straight.
The Nationals arrived in Miami from New York at 4 a.m. but still managed to get off to a fast start. Zimmerman led off the second inning with his fifth homer. Anthony Rendon and Wilson Ramos hit back-to-back doubles, and Taylor hit a two-run homer, his fourth.
''We were operating on a low energy level,'' Baker said. ''The longer the game went, the less energy we had.''
Before the game, Baker said he hadn't been tempted to juggle his rotation so Roark wouldn't face Miami again.
''It's too early to start running from people,'' Baker said.
Roark validated his manager's confidence. He retired the side in order only once but pitched around six hits and two walks.
Shawn Kelley pitched a scoreless eighth and hasn't allowed a run in 15 innings this year. Jonathan Papelbon followed in the ninth for his 12th save. Shortstop Danny Espinosa robbed pinch-hitter Ichiro Suzuki of a hit with a man on to end the game.
''Our bullpen has been great,'' Baker said. ''I'd still like to go a little deeper with our starting pitching.''
The Nationals' Daniel Murphy, who came into the game leading the majors in batting, went 0 for 4 to drop his average to .387. Teammate Bryce Harper doubled and was intentionally walked. Jayson Werth had two hits on his 37th birthday.
Before the game, the Marlins activated RHP Edwin Jackson, who had been on the DL since April 19 with a strained right triceps.
Marlins: LHP Mike Dunn (forearm) is scheduled to pitch a simulated game Saturday at Marlins Park, and remains on schedule to return by early June.
RHP Jose Fernandez (5-2, 3.21) tries to improve to 21-1 at Marlins Park when he pitches Saturday for Miami against RHP Joe Ross (3-3, 2.63).