Braves slugger Mark Teixeira hit two home runs Sunday and might have increased the likelihood that he'll get to play in his first postseason.

With another team.

Rich Addicks/raddicks@ajc.com (ENLARGE)

Atlanta Braves catcher Corky Miller hangs onto the ball, forcing out Washington Nationals Jesus Flores in the third inning.

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The Braves turned in one of their worst performances, getting hammered 15-6 by the last-place Washington Nationals to drop what some Atlanta players characterized as a must-win series.

"Pretty embarrassing," Teixeira said after the Braves made four errors in a game they trailed 12-2 after 3-1/2 innings. "We didn't do anything it took to win a game.

"It's tough to swallow when you're in a must-win situation and come out completely flat. Offensively, defensively, pitching — we didn't do anything right. As bad as you can play a game, that was it."

Their 11th loss in 17 games came against the team with the worst record in the league, at a time when the Braves needed a winning surge to justify being buyers instead of sellers before the July 31 trade deadline.

"Bad day," said manager Bobby Cox, whose fourth-place Braves have lost 12 of their past 18 home games and fallen to six or more games behind three teams in the National league East -- co-leaders Philadelphia and New York, and Florida.

"Bad ballgame," he added. "We can do better than that, for sure."

If they don't, quickly, the Braves might trade Teixeira and perhaps left-handed reliever Will Ohman, both eligible for free agency after the season.

"We wanted to win the series, and I just didn't give the team a chance to win," said left-hander Jo-Jo Reyes (3-9), who was charged for six runs in 2-1/3 innings and lost his fifth consecutive start.

The series figured to be the soft opening of sorts to a critical nine-game stretch for the Braves following the All-Star break, a stretch that continues with a trip to Florida and Philadelphia beginning Monday.

"This nine-game stretch is going to determine whether we buy or sell," third baseman Chipper Jones had said Sunday morning. "[Playing] .500 in this stretch is not going to do it. Below .500, we're in trouble.

"If we play above .500, have a good stretch, we're right in the thick of it."

To play above .500 in the three-series stretch, the Braves would now need to go at least 4-2 at Florida and Philadelphia. They are 5-4 against the Marlins this season, and 1-8 against the Phillies.

"The season's not over," said Teixeira, who has inexplicably hit .379 with 12 homers and 41 RBIs in 31 day games, compared to .229 with seven homers and 31 RBIs in 59 night games.

"We're going to keep fighting. But we need to go on a major roll. We need to do more than win series."

After Reyes was rocked, reliever Buddy Carlyle added fuel to the fire, giving up a career-high six earned runs in 1-2/3 innings.

The Braves set a season-high for runs allowed, matched season-highs for errors and hits allowed (17), and watched Washington's Jesus Flores rack up a career-high five hits as the Nationals set a Washington franchise scoring record.

Atlanta also stranded two runners in each of the first two innings.

Former Braves outfielder Willie Harris had a homer and five RBIs for the Nationals, giving the Cairo native seven RBIs in two nights and 10 RBIs against the Braves this season, half of his season total.

It was a well-rounded debacle by the Braves before 29,320, which raised the series total to nearly 112,000 fans. Many of them went home unhappy after seeing the Braves lose the past two days while giving up 23 runs and 31 hits.

"[In] all aspects of the game, we just got our butts kicked," said Teixeira, in no mood to enjoy his second multi-homer game this year and 20th of his career.

Did the ugly loss make him think about the possibility he could be traded?

"Yeah. That's part of the game," he said. "I've always said I want to stay here and see this thing through. But at the same time, business is business, and sometimes things have to change."