At 3 p.m. Monday, it became official: The Washington Capitals had their team. The NHL’s trade deadline had passed, and after making a pair of moves in the days leading up to it, General Manager Brian MacLellan examined his roster and considered it an improvement over last year’s — which won the franchise’s first Stanley Cup after posting an identical record to this team through 63 games.

Washington’s 64th game, against the lowly Ottawa Senators, started poorly but turned into a puck-possession clinic as the Capitals reeled off seven unanswered goals to top the Senators, 7-2, at Capital One Arena. The Capitals didn’t hit their stride last season until after the trade deadline, and Tuesday’s game was an encouraging sign that this year could unfold in similar fashion.

As Washington looks to stay in playoff position down the stretch, matchups with inferior opponents, such as Tuesday’s, are the kinds of games the Capitals should win handily. Given the New York Islanders’ 3-1 loss to the Calgary Flames on Tuesday, the Capitals have tied New York in points (79) atop the Metropolitan Division, but the Islanders have played two fewer games. The teams will face off in Washington’s next game, Friday on Long Island.

“That was a pretty good push from us today, and that was exciting to watch our team play like that — the enthusiasm, the buy-in, the excitement that now this is really our group,” Capitals Coach Todd Reirden said. “Today was the first time that you could feel it, that this is the group and that we’re all in this together and we’re going to push.”

The Capitals were buyers ahead of the trade deadline, acquiring speedy forward Carl Hagelin and steady defenseman Nick Jensen. The Senators have the league’s fewest points, and they got significantly worse by selling off three of their best players — forwards Mark Stone, Matt Duchene and Ryan Dzingel — for draft picks and prospects. But in the first 10 minutes Tuesday, it was hard to tell which team hopes to contend for the Stanley Cup and which is rebuilding.

Oscar Lindberg was one of the players Ottawa got back from the Vegas Golden Knights for Stone, and he scored 3:16 into the game after the Capitals were unable to move the puck out of their zone. Then Washington right wing Travis Boyd was called for slashing 5:22 in, and another new acquisition got on the board for the Senators. Anthony Duclair, shipped to the Senators when Dzingel went to the Columbus Blue Jackets, beat Braden Holtby with a perfectly placed wrist shot from the left faceoff circle at 7:10.

The Capitals finally recorded their first shot on goal 10:08 into the game, which prompted some sarcastic cheers from the home crowd. By that point, Ottawa had nine shots to go with its 2-0 lead.

“It didn’t look like the boys were too interested to start the game,” forward T.J. Oshie said. “But a good response — not only the goals after we got down two, but I think style of play picked up. We kind of grabbed that game. You never know if they get another one, where that one goes. It was nice to see the boys grab it and really start playing our style on a night where I think it was really important that we stuck to the basics and played our hockey.”

Washington, which finished with 37 shots, tied the score by the end of the first period before turning the game on its head entirely. With 3:03 left in the period, forward Tom Wilson finished a pretty passing play, tapping in a feed from captain Alex Ovechkin. As that goal was being announced, center Lars Eller one-timed Dmitry Orlov’s setup into the net at 17:50 for two goals in 53 seconds.

The Capitals poured it on in the second period. They held the Senators without a shot on goal for nearly the first 10 minutes, and Washington got goals from defenseman John Carlson (a blue-line blast on the power play), Oshie (off a rebound), right wing Brett Connolly (also off a rebound) and Oshie again (on an odd-man rush). This game got Oshie to 20 goals — he is the team’s second-leading goal scorer — and Connolly’s 16 goals are a career high.

Reirden said he tried to put Oshie on the ice with different lines twice late in the game, to give him a leg up while he hunted a hat trick, but the right wing refused.

“That tells you about a person,” Reirden said. “Not refusing in a bad way. Like, I tried to put him up with different lines, and he’s like, ‘No, I’m good.’ That just says about him. How about how he chased down an icing in the second period and won that race? Same guy who comes back in the third period and takes the wide lane when we’re ahead 7-2. This is a teammate. This is a leader. This is a Washington Capital.”

Despite their second-period four-spot, the Capitals had reason for concern as they returned to the dressing room. With less than six minutes left in the period, a dump-in glanced off the hand of center Evgeny Kuznetsov, who departed for evaluation. The injury scare apparently was just that; he returned for the start of the third period and promptly joined in on the fun, adding a goal, his 17th of the season, just 17 seconds in.

“We know we need to be playing well 15 games on until the end, and then it becomes kind of habits and then we just go forward and see what kind of happens,” Connolly said. “It’s been a good little stretch here. We’re starting to get better.”