Nationals starting pitcher Gio Gonzalez looks away after giving up a two-run home run to Justin Upton in the first inning. (David Goldman/Associated Press)

There is something that changes about the Washington Nationals when they play the Atlanta Braves. Players and the new manager will not publicly admit it — in fact, General Manager Mike Rizzo confidently believes the Nationals are a better team than the Braves — but there are few ways to explain Washington’s uncannily ugly performances against its fiercest division rival.

The two teams have played six times this season already, and the Nationals have won only once. All five of the Nationals’ losses through 12 games have come at the hands of the defending National League East champions, capped by a gory weekend and sweep here. Sunday’s deflating 10-2 loss was another clumsy misstep in the Nationals’ efforts to overcome their struggles against the Braves.

Since the start of the 2013 season, the Nationals are 7-18 against Atlanta, including 4-9 at Turner Field. In that span, the Nationals are 86-60 against everyone else. It is only the second week of the season, and the Nationals will face the Braves 13 more times this year, but their hope of getting off to a strong start in April has been stunted by their own struggles against the Braves.

When does the disparity in head-to-head results between two good teams reach frustration level in the Nationals’ clubhouse? “About 30 games ago,” shortstop Ian Desmond said.

The Nationals were outscored 23-11 and committed five more errors than the Braves in the series. Two weeks into the season, Atlanta has won a game started by each member of the Nationals’ rotation. Before the game, however, the architect of the Nationals’ roster refused to relent that the Braves alter his team’s performance.

“They’ve come out on the winning side of it more than we’d like,” Rizzo said. “But we feel confident against this team. We feel we’re better than this team. We respect them, and we respect their organization. But we don’t fear them. We think we’re the better team, and at the end of the day we’re going to come out on top.”

With every game of this weekend’s series, the Nationals got progressively worse. In the first two innings of the three games combined, the Nationals were outscored 14-1. The Nationals came back in a wild game Friday before losing. They could have done the same Saturday but failed to convert myriad opportunities. On Sunday, they just looked overmatched. The Braves have noticed a trend in their familiar opponents.

“When we’re out there playing them, we do well for whatever reason,” Braves shortstop Andrelton Simmons said. “If anything it might be in their head.”

The Nationals have been hampered early this season by injuries. Hours before Sunday’s game, Ryan Zimmerman was officially placed on the disabled list with a fractured right thumb. He joined Denard Span (concussion), Wilson Ramos (hand surgery), Doug Fister (lat strain) and Scott Hairston (oblique strain) on the disabled list. And nearly 30 minutes before the game, starting center fielder Nate McLouth was scratched from the lineup after an old knee injury flared up. But the Braves, too, have been slowed by injuries.

“The rest of the league doesn’t care,” Rizzo said. “We’re just trying to work our way through it.”

By the second inning of Sunday’s game, as Braves hitters battered Gio Gonzalez to take a 6-0 lead, the on-field horror scene felt all too familiar. While Bryce Harper and Kevin Frandsen again proved to be bright spots in the lineup, the entire offense mustered only two runs and stranded five runners. The Nationals committed three defensive errors on Sunday, bringing the total for the Atlanta series to seven. Then it got worse: Ross Detwiler surrendered four runs in the eighth inning of an already out-of-reach game.

“They’re a good team,” Harper said. “They play very well here. We try to come in here and win ballgames. And sometimes it doesn’t happen. They’re a great team. They’re a great organization. They hit homers and doubles a lot these past three days. And they didn’t make many mistakes. You gotta tip your cap.”

Gonzalez left his fastballs over the plate too often, and the Braves clobbered them. Justin Upton clobbered a two-run home run to center field for a 3-0 Braves lead in the first inning. Gonzalez pointed up in the air, thinking it was a flyball, but it carried just over the fence.

An inning later, Gonzalez surrendered a leadoff triple to Tyler Pastornicky, the second one surrendered in two innings, and an RBI double to Jason Heyward. Two batters later, Freeman hit a Gonzalez pitch higher than he did far, but the ball managed to stay fair and landed in the right field seats for a two-run home run and a 6-0 lead. The expression on Gonzalez’s face was of disbelief. And Nationals fans probably felt the same way: How can this team keep doing this against the Braves?

“We’re shooting ourselves in the foot,” Desmond said. “You can’t be mad at anybody but yourself. So you swallow that down and keep on playing and you’re still going uphill. No one is going to sit in the corner and cry about it.”

Braves starter Aaron Harang, who was released late in spring training by the Cleveland Indians, held the Nationals to one run on five hits and struck out five batters over six innings. The Braves’ strong bullpen allowed one run over the final three innings, a solo home run by first baseman Adam LaRoche.

Washington’s pitching staff couldn’t limit two of the Braves’ best hitters. Freeman has crushed the Nationals through two series: He is 11 for 22 with two home runs and five RBI against them this season. Upton has caught fire over the past week and smashed two home runs and had five RBI against the Nationals this series.

The Nationals will play the Marlins in Miami over the next three games and, in their minds, hopefully put distance from the latest shortcomings against the Braves. The next time the two teams play will be in the heat of the season and summer in mid-June.

“We know we can play with them,” Desmond said. “Maybe try something different next time.”