Capuano earned his career-high fifth straight win Sunday, allowing four runs and seven hits over five innings of an 8-4 victory over Atlanta.
The left-hander walked two and struck out six, becoming the first Milwaukee pitcher to reach 10 wins prior to the All-Star break since Teddy Higuera in 1986.
“I just told myself to bear down and give it all I got,” said Capuano, who threw 100 pitches. “When I look back, it could have been a lot worse. In retrospect, I’m pleased.”
Washington, baseball’s biggest surprise in the first half, has dropped two straight since the break, including a tough 4-3 setback to Milwaukee on Friday night.
Making his first appearance for the Nationals since signing with the team on Wednesday, left-hander Mike Stanton balked in the winning run in the bottom of the 10th inning. Stanton was trying to pick off Rickie Weeks from first base before he even threw a pitch.
First base umpire Paul Schrieber immediately called a balk, allowing Chris Magruder to score from third.
“That is my typical move,” Stanton argued. “He said I went to the plate. No, I didn’t. It’s just unfortunate a game had to end this way.”
Manager Frank Robinson backed his new reliever.
“This is compared to a referee in the NBA with one-tenth of a second on the clock and he calls a touch foul and sends the guy to the free-throw line to win a ballgame,” Robinson said. “They don’t do it. This one shouldn’t have ended up like that.”
The defeat shaved the Nationals’ lead in the East to just 1 1/2 games over perennial division champion Atlanta.
Esteban Loaiza will try to help Washington bounce back Saturday. He allowed two runs and six hits over six innings, but didn’t receive a decision in the Nationals’ 5-4 loss at Philadelphia on Sunday.
It was just the second time in Loiaza’s last seven starts that he failed to register a victory.