Capitals goalie Braden Holtby looks on from the bench after being replaced by Philipp Grubauer during the third period of a 6-2 loss to Pittsburgh on Sunday. (Gene J. Puskar/AP)

With their 52nd win, the Washington Capitals took another step toward rendering the rest of the regular season meaningless. Playoff berth? Check. Metropolitan Division title? Check. Top seed in the Eastern Conference? Check. All that’s left is the Presidents’ Trophy, and that could be secured this week.

Did the Capitals have a celebration after the 4-2 win in Ottawa?

“Yeah, lots of champagne,” Nicklas Backstrom joked as he stood on a suspiciously dry locker room floor.

There was no champagne and not many smiles Tuesday night. Rarely has a winning locker room seemed so frustrated with its performance. For the Capitals, it wasn’t just this game, but months of games and a realization that they aren’t as dominant as they were earlier in the season — and that they’re running out of time to return to their best before the playoffs start.

“I think we’re all kind of sick of the way we’ve played at times the last couple of months,” goaltender Braden Holtby said. “You can tell it’s starting to turn, just everyone’s realizing we have kind of hit that bottom.”

“Bottom” sounds harsh for a team with 109 points and 10 games to play, and since the all-star break, the Capitals are 17-7-1. But in that time, the Capitals’ goal differential is plus-five. Anaheim’s is plus-28 and Pittsburgh plus-23. Old bad habits of slow starts were resurrected: Of those 25 games, Washington trailed first 18 times. The ability to win the majority of those games was always a strength, but the constant rallies became bittersweet because the Capitals were exasperated with consistently giving up the first goal and then consistently having to talk about their tendency to give up the first goal.

Games such as Tuesday night’s add to the frustration; Washington started strong with a three-goal first period and then faded, letting the Senators creep back in. That was on the heels of Sunday night’s 6-2 loss at Pittsburgh that showed the difference between a team battling for postseason positioning and one such as Washington, which has been waiting and waiting for the finish line to get here already.

Even the Capitals are starting to question whether they’d be ready for the postseason if it started immediately. Previous Washington teams have arguably peaked too soon and suffered early playoff disappointment. Backstrom dated the Capitals’ struggles to even earlier than the all-star break.

“We have 10 really important games,” Backstrom said. “We haven’t played our best hockey since after Christmas, so we have some areas we have to get better on and make sure we play a full 60-minute game.”

What’s the cause of the second-half stumbles? It’s hard to know, but defenseman John Carlson suffered a lower-body injury in the game immediately after the Christmas break, and he hasn’t been completely healthy since. After Carlson returned to the lineup just before the all-star break, his injury lingered and he had a procedure in late February. He is expected to play again as soon as Friday in New Jersey.

His absence put a greater strain on a defense that was already without defenseman Brooks Orpik, who missed 40 games with a lower-body bone injury. Orpik is back, but the Capitals haven’t had a healthy lineup since November, the blue line seeing most of the personnel shakeups. Washington managed spectacularly under the circumstances, but with the defense suspect at times, the goaltending suffered — and maybe Holtby just wasn’t as sharp, too. In his 21 starts entering Tuesday’s game at Ottawa, Holtby had a .903 save percentage.

The mammoth lead in the standings has also played a part.

“The blessing of where we are is we’ve got room and we can try things, and the curse is where we are,” Coach Barry Trotz said. “That’s what we’re battling a little bit. . . . It’s been hard to manufacture urgency. You can’t.”

The Capitals appear to be feeling it now.

“It’s one of those things where we’re not in a playoff push, but now with 10 games left and we’re not playing the way we want to play, it’s almost a blessing in disguise that we can ramp it up,” Holtby said. “Now we have something to play for. We want to make sure we’re getting to our top level coming into Game 1 of the playoffs, and it’s a luxury that we have 10 games to do it. Now it’s our job to use them effectively, and that’s our goal as a collective group.”