Nationals center fielder Jeff Kobernus fails to corral the ball at the wall on what turns out to be a triple by Philadelphia’s Michael Young in the third inning. (Matt Slocum/Associated Press)

Distill the first 21 / 2 months of the Washington Nationals’ season into one inning, and you may produce something like the gut-punch ninth that capped their 5-4 defeat against the Philadelphia Phillies on Monday night. Soaring buildup dissolved into a miasma of things gone wrong — lack of execution here, a bad break there, a dash of curious management, all stirred together to maximize anguish.

In the top of the ninth, the Nationals reached their last out, their last strike and, as Chad Tracy hacked away against Jonathan Papelbon, their last centimeter. Tracy fouled away consecutive 0-2 pitches from the fire-breathing closer, first a fastball and then a splitter, with which he barely made contact. The ball trickled away. The crowd roared. The next pitch came in.

Tracy walloped a high flyball over the right field fence, a thunderbolt that served to overshadow an unavoidable subplot and illustrate the Nationals’ staggering propensity for spoiling their brightest moments. Tracy’s homer robbed John Lannan the chance to earn a victory against his former team and pushed the game into the bottom of the ninth. Domonic Brown’s two-out single off Fernando Abad — the minor league free agent Manager Davey Johnson had chosen to navigate a tie game — gave the Nationals a walk-off loss.

“We just can’t get anything going,” third baseman Ryan Zimmerman said.

Mid-June is no time to erect tombstones, but if it was, Zimmerman’s words would be etched across the Nationals’. They have lost three of their last four and, at 34-35, sat seven games behind the Atlanta Braves in the NL East standings when the game ended.

They entered the year World Series favorites in part because they let Lannan walk and signed free agent Dan Haren for $13 million. On Monday night, Haren allowed four runs in six innings, yielding three walks and seven hits, avoiding his ninth loss only because of Tracy’s homer. Lannan, making his first start against the franchise for which he twice started on opening day, allowed two runs in five innings.

“I knew I had to do a job no matter who I was facing,” Lannan said. “They have some good hitters over there, so I really had to bear down at times. But there was no extra emotion.”

The game would be decided after both Lannan and Haren exited. In the eighth, Ian Desmond ripped a two-out, RBI single up the middle. In the bottom half, Tyler Clippard struck out Laynce Nix with the bases loaded to keep it a one-run margin.

After two quick outs in the ninth, Papelbon seemed ready to slam the door all the way shut. He fired a 93-mph fastball over the inside corner, higher than he wanted and not far enough inside. Tracy turned and crushed it. John Mayberry Jr. trotted to the wall, only for posterity. The Nationals had tied the score at 4.

“I think all of us had a feeling,” Tracy said. “We expected to win, sure. You tie it up late and everybody’s emotions are running high and everybody’s feeling good.”

The homer provided Johnson with a choice: Who should pitch the ninth inning? On Friday, he had tabbed Abad in a tie game in the bottom of the ninth, which led to a walk-off loss in Cleveland. Monday night, he again chose Abad, who had impressed this year after the Houston Astros released him this winter, over Drew Storen, who in 2011 recorded 43 saves.

Johnson had his reasons. He wanted Abad to face leadoff hitter Ben Revere, a left-handed hitter — Storen had allowed lefties a .353 batting average this season. He also wanted to avoid putting Storen in with a runner on base — 14 base runners have attempted to steal off Storen in his career, and 13 have been successful.

“If he gets him,” Johnson said, “I go to Storen. If he doesn’t, he’s got to hold the guys on. It’s that simple.”

When Revere greeted Abad with a hard single up the middle, Johnson already had his mind made up. The inning belonged to Abad.

“I feel comfortable whenever Davey calls my name,” Abad said. “Whatever he wants, I’m ready for.”

With one out, Jimmy Rollins singled to place runners on the corners. Abad nearly wiggled out of the jam. He whiffed pinch hitter Steven Lerud with a high fastball. Against Brown, he worked the count to 2-2 and then fooled him, it seemed, with a 93-mph fastball on the inside corner. Brown nubbed the ball with the end of his bat and lined it into center field. Abad swung his arm and walked off the field with his head down.

“Broken bat,” Abad said. “He put it in the right spot.”

The Nationals lost the game in the ninth, but the Phillies had seized control against Haren, whose ERA leveled at 5.72. He entered the night with the chance to notch a win against his 30th franchise, a testament to his sterling career. Four batters into the game, Ryan Howard launched a homer into the upper deck, the league-high 18th home run Haren has allowed.

Haren has suffered something of an identity crisis this year, trying to figure out how to pitch with diminished stuff. Take the third inning, the moment it spiraled.

Michael Young smoked a line-drive triple to center field with one out and the game tied at 1. Typically aggressive, Haren altered his approach, in part, because of the Nationals’ sagging offense. He tried to make perfect pitches against Rollins and Howard. He walked both of them, and Delmon Young followed with a well-placed, two-run double to right, just out of Jayson Werth’s reach.

“My game isn’t nibbling around the zone,” Haren said. “My game is attacking hitters. The runs have been somewhat of a premium. I tried my best to keep that run from coming in, which getting to two outs and the bases loaded and the ball falls in. A little bit deflating. I can’t buy a break, and I’ve obviously made my share of mistakes. Just not a good combination.”

The Nationals will try again Tuesday to start a run, to get something going. In the clubhouse afterward, Ian Desmond and Kurt Suzuki spoke in hushed tones, dissecting what had gone wrong, even after it seemed something had gone so right.

“Right after the game, there’s really nothing to think about but the bad stuff,” Zimmerman said. “It’s a loss, and it’s tough to handle.”