How do you explain a dream gone suddenly dark? During last week's tumble through the National League East standings, this question vexed the Washington Nationals, answered more with slammed bats and thrown batting helmets than with tangible responses.

They spoke in confused tones, with shaking heads and arms spread wide as they searched for the missing ingredient to a season turned bad. But what that ingredient was they didn't seem to know. Was it luck? Was it skill? Was it desire that got them to 52 wins and first place at the All-Star break?

And if so, why had it disappeared so fast? The best answer seemed to lie in the results of one-run games, normally a reliable barometer of a team's resiliency. On July 8, the Nationals were 24-8 in one-run games. Since then they are 0-10 in such situations. Still, all that says is Washington can't win close games the way it once did. There lingered a deeper solution, something felt but unable to be grasped.

That was what frustrated them so, what caused players to slump in their lockers and what led to two closed-door team meetings in three days.

"I didn't expect us to go the whole year the way we were playing," Manager Frank Robinson said. "I didn't think we would walk on a tightrope all year. Eventually you fall off."

The Nationals do not have a lineup that pops. Much of the time it barely fizzes. They are last in the National League in runs, hits, total bases, home runs, RBI and stolen bases. In other words, they aren't going to score many runs. And since their team ERA has dropped every month of the season, the problem lies somewhere in the extra run they used to get, the one that made the difference in half of their first-half victories.

"We're playing just good enough to lose by one," said reliever Mike Stanton, recently acquired from the Yankees. "How do you change that? We make one mistake here, one mistake there; that's all it takes to lose. We aren't a team that can cover our mistakes. We have to play pretty flawless baseball. When you have a power-packed lineup like we did in New York, those things don't hurt you as much.

"If you're down two or three, a walk and a bloop and a blast and you're back in it. With this team it's a walk and two singles and you still don't have a run."

Robinson doesn't believe his team was playing flawlessly in the first half, quite the contrary. While the statistics showed the Nationals were one of the best defensive teams in the majors, he saw blunders that worried him. Perhaps it was a bobbled ball that prevented a double play from being turned or a throw to the wrong base that allowed a runner to move up -- mistakes that didn't show up in box scores or were minimized and eventually forgotten when the other team didn't score.

Suddenly those errors seem to matter. The ground ball that was bobbled allows a runner to score these days. The throw to the wrong base is bringing the decisive run home. For most of the past few months, shortstop Cristian Guzman and third baseman Vinny Castilla have not been hitting. Guzman's average is at .186; Castilla's is at .246. Together they have just 58 RBI. Their offensive ineptitude was considered acceptable as long as they played good defense. But lately both players have started making defensive errors or, particularly in Guzman's case, missing balls they probably should have had.

Still, the errors could be overcome if the team could simply put together a rally. Too often it can't string together more than a pair of singles. Its average with less than two outs and runners in scoring position (the best conditions under which to generate rallies) was .149 in July. In baseball, production in such situations is called timely hitting. And in the season's first three months, no team seemed better at it than Washington.

The Nationals weren't getting that many more hits then than they are now, but they were making the most of the ones they got. If a batter doubled, he went to third on a ground out, then scored on a sacrifice fly. Now if a runner gets to second, he more than likely will be stranded there.

Robinson attributes some of the struggles to injuries suffered by second baseman Jose Vidro -- once considered the team's best hitter -- and Nick Johnson, the first baseman who thrived on timely hits in the first half. Neither has been as crisp at the plate since returning to the lineup, Johnson's two RBI in Sunday's 4-2 victory over Florida notwithstanding.

The common perception around baseball is that the Nationals were just not as good as their record indicated: They were actually outscored in the season's first half, despite a winning percentage that was at times over .600. But General Manager Jim Bowden disagrees. He surmises that the bulk of the players on this team have actually performed well beneath their potential.

"Of our starting eight, I'd say there are only two players who are playing to expectations," Bowden said the other night in Atlanta. One is undoubtedly Jose Guillen; the other is catcher Brian Schneider. Johnson and Vidro have been hurt, and the others -- Castilla, Guzman, Brad Wilkerson, new acquisition Preston Wilson -- have numbers below their career averages.

"If you look at the first half we didn't have anyone having a blowout year except [pitcher] Livan Hernandez," Robinson said. "What we may have overachieved at is the winning of the one-run ballgames. That is team baseball. We're just not getting the timely hit."

What Robinson thinks is missing most is the sense of invulnerability, a sense that his team will come back even if it falls behind.

"It got to be a joke with us," he said. "Don't worry about the first five innings, we'll win it."

Perhaps more than anything it is the disappearance of this -- what the athletes often call the swagger -- that perplexes him most. He knew the offense would slump, he figured there would probably be some defensive lapses, he knew the team wasn't as good on paper as many of the others in the division. But he believed in its resilience, shaking off the notion that the grind of 34 one-run games in the first half of the year would have a fatiguing effect.

He knows people are saying this team is flawed, that no one thinks a club can go to the World Series based on its fight in one-run games alone. Still, he refuses to listen.

"Just because something hasn't been done, can it not be done?" he asked. "Of course not."

His challenge now is to convince his players of the same thing.

In a typical scene of late, Atlanta's Jeff Francoeur scored on a wild pitch last Wednesday as Washington's Joey Eischen was helpless to stop him.