WASHINGTON -- For the past two months, the Nationals have posted the best record in baseball, a torrid stretch since May 24 that has turned around their season and put them right in the midst of the National League postseason picture. But this six-game stretch will serve as a measuring stick against the only two teams in the NL who began the day with a better record than them.

It made for a playoff-like atmosphere Friday night in front of 37,491 fans at Nationals Park, as the Nationals began a three-game series with the Dodgers, who own the best record in MLB. But a 4-2 loss to Los Angeles once again highlighted Washington’s biggest flaw, a leaky bullpen that threatens to derail this Nationals season.

• Box score

After a pitchers’ duel for seven innings between Dodgers left-hander Hyun-Jin Ryu and Nationals starter Anibal Sanchez, the Nats’ bullpen could not keep the game knotted at 1. Kyle Barraclough, who was called up from Double-A Harrisburg earlier in the day and pitching in his first game in the Majors since June 15, surrendered a three-run homer to Justin Turner that provided the difference. It’s the first time the Nationals have dropped back-to-back games since June 22-23, and both losses have come at the expense of their bullpen.

“It's just a matter of executing pitches,” Barraclough said. “Miss up and in to a guy that likes the ball up there, and obviously after the first couple pitches that I threw up there he's just looking for it, so I just got to execute better.”

Barraclough was not the only Nats reliever who struggled during the eighth inning. Tony Sipp was brought in with two outs to retire either of the lefties at the top of the Dodgers lineup. Instead, he walked Joc Pederson and surrendered a single to Alex Verdugo. Then with runners on first and second, manager Dave Martinez turned to Barraclough, who has struggled mightily pitching with inherited runners all season. Barraclough has now allowed 11 of 13 inherited runners to score.

“I think at this point it’s a confidence issue,” Martinez said. “He threw the ball by Turner at 96. And then all of a sudden he threw one to the backstop. I could see a little bit of hesitation. And then all of a sudden he couldn’t locate his fastball. That last pitch was up, but it was right down the middle. He’s just got to get confidence. He’s got to come back with confidence.”

Martinez was managing with a few of his most trusted relievers -- Tanner Rainey, Wander Suero and Fernando Rodney -- all unavailable after heavy workloads in recent days. So, he was going to have to build a bridge to Sean Doolittle without his best options in relief, but this Nats bullpen has needed help for months. The Orioles 'pen began the day as the only team in baseball with a higher ERA than the Nationals.

It’s why acquiring a reliever is the Nationals' top priority before the Trade Deadline passes on Wednesday. They received elite starting pitching from Sanchez, and their offense rallied against Ryu and nearly came back against Kenley Jansen in the ninth inning.

By next week, perhaps Martinez will have Royals left-hander Jake Diekman to use in the eighth inning instead of Sipp, or Shane Greene of the Tigers instead of Barraclough. Washington has reached out to check in on both players, as well as Sam Dyson of the Giants and likely any other reliever who will be made available before the end of the month.

Adding another piece to its bullpen will be crucial if Washington wants to win games like this in October, in what could be the difference separating the club from the favorites in the NL.

“I truly believe that we match up really well with them, we do,” Martinez said. “And we saw that today. It was one heck of a game. It was a lot of fun, the boys were into it, it was exciting, the fans were into it. Let’s come back tomorrow and do it again, and let’s be on top by the end of the game.”

Nats confused about ruling at home plate
The Nationals almost took the lead in the seventh inning after an 11-pitch at-bat from Adam Eaton ended in a run-scoring single against Ryu to plate one run, but Gerardo Parra was thrown out at the plate by Alex Verdugo in left field. Parra was thrown out handily, but Martinez challenged the play because he believed catcher Russell Martin was blocking home plate, leaving Parra with no room to slide, and he was tagged out standing up.

“[Parra] didn’t know what to do,” Martinez said. “[Martin] was right in front of home plate, and the rule apparently states that if he would have slid, they might have called him safe.”

According to Rule 6.01(i), a catcher without possession of the ball shall not be judged to violate [the rule] if the runner could have avoided the collision with the catcher [or other player covering home plate] by sliding.

But because Parra never slid, the umpires could not call Martin for blocking the plate.

“But he didn’t know where to slide,” Martinez said. “He was in front of home plate. It’s something that I don’t understand, because in reality his first thing was to knock him over, we’re all taught to do that, and he didn’t know what to do. So he tried to step around him, so that’s why I came out. … How do you slide when a guy is blocking the plate?”