PHILADELPHIA -- Never in the 53-year history of the Nationals' franchise has the organization had a two-day span quite like this one.

Closer Brad Hand entered with a ninth-inning lead for a second consecutive game in Monday's series opener against the Phillies. And for the second straight game, the Nats lost in walk-off fashion, this time dropping a 6-5 decision at Citizens Bank Park.

Staked to a 5-3 lead, Hand allowed a leadoff double to Jean Segura and issued a one-out walk to Bryce Harper before serving up the walk-off three-run homer to Andrew McCutchen on a first-pitch two-seamer left up in the zone. That came on the heels of Sunday's walk-off loss to the Orioles, in which Hand entered with a 5-4 lead before allowing a pair of runs while again recording only one out.

"It's obviously frustrating. Just making too many mistakes right now," Hand said. "Not executing pitches. I believe in myself. I know that I'm better than that, and just need to make some better pitches."

Hand's lack of command resulted in back-to-back losses unlike any the Nationals had seen before. It's the first time in franchise history that the club took a lead into the bottom of the ninth in consecutive games, only to lose each on a ninth-inning walk-off.

"Losing in general, no one likes. Losing on a walk-off, no one likes," said Joe Ross, who tossed five scoreless innings in his first start since July 4. "Losing back-to-back games on walk-offs is even more tough."

The consecutive crushing defeats extended Washington's losing streak to five games. The team is just 3-11 in its last 14 games dating to July 8.

The recent slide has dropped the Nationals (45-54) to 8 1/2 games back of the first-place Mets in the National League East -- matching their largest deficit of the season. That comes with Friday’s 4 p.m. ET Trade Deadline looming, and plenty of teams reportedly checking in on some of Washington’s biggest stars.

"Tough losses. Of course, the mood is going to be a little dismal right now -- just lost another tough game," said manager Dave Martinez when asked about the emotions in the clubhouse. "Like I always tell these guys, you've got 30-45 minutes to think about the game, then let it go. We've got another game tomorrow."

In what has become all-too-familiar fashion over the past two weeks, it was a disappointing end to a game that began with plenty of promise.

Ross had picked up right where he left off in his return from the injured list, and the Nationals' offense provided some early support behind him. It marked the fourth time in Ross' last seven outings that he did not allow an earned run -- a stretch during which he has a 2.05 ERA.

Washington also looked poised for a big night with its bats, after putting together a four-run, seven-hit inning in the fourth. Josh Bell and Josh Harrison hit back-to-back run-scoring triples to put the Nats on the board, and Gerardo Parra and Victor Robles followed with RBI singles.

Unfortunately, the Nationals did not manage another hit until the ninth, when they loaded the bases with one out but managed to push across only one insurance run on a Didi Gregorius error. Harrison and Parra followed with flyouts to strand the bases loaded.

That quickly came back to haunt Washington, as McCutchen sent Hand's elevated sinker sailing into the right-field seats.

"Just frustrating," Hand said. "To lose another game like that, all on me, it's very frustrating."