Buffalo’s Mark Mancari, center, moves the puck as Jason Arnott, left, and Brooks Laich (21) try to take it away. Capitals Coach Bruce Boudreau has not been happy with his team’s play lately. (Luis M. Alvarez/Associated Press)

Alex Ovechkin’s shot deflected off a pair of skate blades before slipping past the Sabres’ goalie and igniting a raucous celebration at Verizon Center. Fans high-fived and players poured from the bench to congratulate their captain as he did a goofy jig near center ice.

Ovechkin’s overtime goal temporarily put the Capitals back atop the Eastern Conference for the first time in 122 days. But the solemn look on Coach Bruce Boudreau’s face as he stalked into the postgame interview room, his hands stuffed into his pockets, told a different story.

Boudreau wasn’t in the mood to toast the Capitals’ 5-4 victory. He wasn’t pleased with “the process,” which, translated from coach-speak, meant his players’ execution of the game plan left much to be desired. He had also lost reserve defenseman Tyler Sloan to an apparent head injury, dealing another blow to a blue line that’s already stretched to its breaking point.

“I thought it was way too close to looking like last year,” Boudreau said of a contest that began with his team racing out to a 2-0 lead, fumbling it away moments later, then needing a last-minute goal from Jason Arnott to force overtime.

Just a few weeks ago the Capitals were undoubtedly playing the best hockey of the Boudreau Era. Great goaltending, a lights-out penalty kill and an overall commitment to team defense helped them procure seven one-goal victories during a nine-game winning streak.

But it’s hard not to believe that they took a small step backward on the just-concluded three-game homestand — even if they earned five of six possible points.

It wouldn’t have been so troubling had the sloppiness been limited to the Sabres game. But the Capitals coughed up leads in each of the previous two contests, as well. Being forced to overtime by teams significantly behind in the standings isn’t how a team with Stanley Cup aspirations wants to be playing a little more than a week before the start of the playoffs.

“We’ve got to buckle down a little bit,” Boudreau said.

On Tuesday, Carolina rookie Jeff Skinner struck early in the third period, sneaking a sharp angle wrist shot past Semyon Varlamov to knot a game the Hurricanes eventually captured, 3-2, in a shootout. As inexcusable as Skinner’s goal was, Boudreau held the other players just as culpable, describing his team’s performance as “lackluster” and without emotion.

In the waning minutes of Thursday’s game against Columbus, Blue Jackets winger Scottie Upshall somehow slipped loose in the slot and snapped the tying goal past Michal Neuvirth with 5 minutes 37 seconds left to play. Although the Capitals eventually won in overtime, 4-3, Arnott wasn’t particularly impressed with Washington’s attention to detail, saying they made “a lot of nonchalant plays that we don’t normally make.”

Then it happened again Saturday. Buffalo’s Paul Guastad scored the Sabres’ third straight goal after exploiting an ill-timed line change late in the third period, splitting the Capitals’ late-arriving defenders after Scott Hannan’s casual backhanded clearing pass was picked off in the neutral zone.

Then, about four minutes later, rookie of the year candidate John Carlson inadvertently kicked in the Sabres’ fourth goal, sending Boudreau over the edge on the bench.

“He was up on the rush when we were killing a penalty,” Boudreau later explained of his expletive-laden tirade. “Then we have to come back like chickens with our heads cut off, and that why it went in off his foot — because he was working so hard to get back and he wasn’t focused on where it was.”

Suspect goals. Sloppy line changes. Poorly-executed pinches. You name it, and at some point over the past week, the Capitals have been plagued by it.

“Protecting the lead, for the most part this year, was a forte of ours,” Boudreau said.

So was their depth on defense. But not anymore. It’s gotten so bad that the Capitals on Saturday recalled Sean Collins, who hadn’t played in the NHL since 2008-09. Collins didn’t leave the bench late in the third against Buffalo because, Boudreau said, if he made a mistake it might cause his confidence to “go all to hell.” That’s not reassuring at all.

To their credit, the Capitals have managed to overcome the loss of No. 1 defenseman Mike Green, sidelined 23 of the past 25 games with a concussion, when many thought it wasn’t possible.

But now they’re also missing Dennis Wideman, the player General Manager George McPhee acquired at the trade deadline specifically to step in for Green. I’m no doctor, but it doesn’t sound like Wideman’s going to be ready to suit up any time soon, not after being hospitalized last week with a gruesome leg hematoma. Toss in the injuries to Tom Poti, who has been limited to 21 games and hasn’t played at all since Jan. 12 because of a persistent groin muscle strain, John Erskine and Sloan, and the situation seems particularly grim.

Green appears to be inching closer to a return, though, and if he does, that would offset the loss of Wideman. Erskine, meantime, could be back Tuesday in Toronto, while Sloan was well enough to participate in the fan appreciation ceremony after the Buffalo game.

That’s all good news. So, too, is the fact that the Capitals have three regular-season games remaining. That provides Boudreau and his staff with some time to address the hairline cracks that have begun to appear in the foundation of a team that was rock solid for most of March.