William Nylander and the Maple Leafs are making life uncomfortable for the Capitals’ defense. (Frank Gunn /The Canadian Press via AP)

TORONTO — Even in the stretches of the season when the deep, skilled Washington Capitals inconceivably couldn’t find a way to score, the team’s structured defense was a constant. Since Barry Trotz became the coach and General Manager Brian MacLellan signed blue-liners Matt Niskanen and Brooks Orpik three years ago, stingy play became the Capitals’ identity more than offense.

Washington allowed the fewest goals per game in the regular season (2.16), and the Capitals were ranked fourth in shots allowed per game (27.8). It’s head-scratching then that in a first-round series against the young Maple Leafs, Washington has allowed 10 goals in three games and fallen into a 2-1 series deficit.

“We’re the best defensive team in the regular season, and I think we’ve got to get back to that,” forward Daniel Winnik said. “I don’t know how many times we let in four goals in a game during the regular season, but in back-to-back games, it’s, to me, unacceptable.”

Going into the season, with the Capitals returning all seven defensemen along with starting goaltender Braden Holtby and a structured forward corps, they allowed four-plus goals just 15 times in an 82-game season. The development of young blue-liners Dmitry Orlov and Nate Schmidt strengthened the team’s defense even more, and Orlov’s improvement in particular enabled the Capitals to play the 36-year-old Orpik on a third pairing. He’s thrived with fewer minutes against lesser competition.

Washington then traded for defenseman Kevin Shattenkirk, and the addition of the offensive puck-mover gave the Capitals arguably the deepest blue line in the NHL. It was supposed to be their greatest edge on the Maple Leafs, especially in the first two games when Toronto was without Nikita Zaitsev in their top-four.

Instead, the Capitals’ defense has arguably been its Achilles’ heel. By virtue of being a veteran team, Washington doesn’t have the quickness that the spry Maple Leafs do, and it’s shown. Toronto is often beating the Capitals to pucks on soft dump-ins. Washington is missing defenseman Karl Alzner, who’ll miss a second straight game on Wednesday night with an undisclosed upper-body injury, but the Capitals got an injection of speed on the blue line with the addition of Schmidt. Schmidt was on the ice for every Washington goal in Game 3.

Toronto’s speed has also been a pain through their forechecking, causing the Capitals to be uncharacteristically sloppy on breakouts. On Tuesday, they discussed moving the puck out of their own zone with more urgency.

“Our cleanliness on our breakouts, getting out on our first try and making sure we’re not turning pucks over at the blue line, I think that’s the biggest part,” Schmidt said. “They’re doing a good job of hounding us and hounding our D and making sure that they’re pressuring us into situations that you sometimes don’t want to be in. So, you’ve got to make sure just to be quick and make sure we get out of the zone a little bit faster.

“It’s something that revolves around all five of us, even Holts [Braden Holtby] as well, making sure that we’re on the same page and kind of exiting through him a little bit more. He talked about it today in practice, kind of talking about moving pucks faster between him and I and the defensemen. I think it’s something that they’ve been doing well. They’ve been pressuring us and making it tough on us, but that’s going to be the biggest part of our game that we need to clean up moving forward.”

Shattenkirk wants to see more patience from himself and his fellow defensemen. On the game-tying goal, he and Orpik both went to check Zach Hyman beyond the goal line, and William Nylander was left all alone in front of Holtby, getting off two shots.

“I think we just have to stop when we get back to our net front, be a little more patient,” Shattenkirk said. “I think they’re doing a good job, they’re pretty slippery in the corners, but the problem is we’re sending a second guy in there and he feels like he needs to go help or help his teammate recover. But we’re still in pretty good position. So I think we need to just be a little bit more patient and we’ll find that pucks are going to come to us in the middle of the zone and we’ll be able to break out.”