Torey Krug’s injury adds to Bruins’ problems

Torey Krug (left) was skating on the Bruins’ No. 2 defensive pairing alongside Adam McQuaid prior to his injury Tuesday.AP

WILMINGTON — Amid the uncertainties a hockey season can bring, the Bruins believed there were three things they could count on.

Zdeno Chara would be a shutdown monster. Brad Marchand, Patrice Bergeron, and Reilly Smith would form a thorough, efficient, and productive three-zone line. Torey Krug would keep the power play humming as the first unit’s quarterback.

On Wednesday at Ristuccia Arena, Chara hobbled through the dressing room after practice without bending his injured left knee. Marchand and Smith were demoted to the third and fourth lines, respectively, because of their misfiring play. Krug was out of uniform because of a broken finger on his left hand, courtesy of a third-period Zach Parise slash in Tuesday’s 4-3 loss to Minnesota.

Marchand didn’t even complete the practice. He pulled out early because of an undisclosed injury. Although Marchand planned to travel to Buffalo, his availability for Thursday’s game is undetermined.

“It doesn’t really matter who you’re playing with on this team,” said Bergeron, who centered Chris Kelly and Simon Gagne in practice. “It’s about doing your job and helping the team.”

Because of Chara’s injury, Krug had been playing on the second defense pairing with Adam McQuaid. Krug assisted on Milan Lucic’s power-play goal on Tuesday with a clever shot pass to his teammate’s blade.

Now Krug (2-4—6, 20:28 of ice time per game) is out 2-3 weeks. His absence puts the Bruins down three defensemen, along with Chara and Kevan Miller.

The Bruins recalled David Warsofsky and Joe Morrow from Providence Wednesday. Warsofsky will most likely make his season debut against Buffalo as Zach Trotman’s partner on the No. 3 pairing. Warsofsky could also see time on the power play in Krug’s position.

Warsofsky was in the Bruins’ plans to open the season with the varsity. But the former Boston University defenseman did little to stand out. The Bruins assigned him to Providence, where he did not start well. He has not scored a point in seven games.

“Every time you get demoted from a position you want, I think you’re going to be a little bit disappointed,” Warsofsky said. “I tried to shake that off. It’s part of the business. I knew at some point my opportunity would arise again. I just have to take advantage of it.”

The Bruins would be in a better position to absorb Krug’s loss if they were getting useful shifts from Matt Bartkowski. When Bartkowski is feeling good about himself, he pushes the puck out of the defensive zone to trigger the breakout. He has been a trustworthy second-pairing defenseman before.

But Bartkowski has lost the trust of his coaches. He was on the ice for two of Minnesota’s four goals. After the second, Bartkowski didn’t play another shift. He played a team-low 8:56. His frazzled mental state has caused his game to crumble.

“The hardest way to play is the way I’m playing right now, which is playing not to make mistakes,” Bartkowski said. “Once I put a shift out there where I just go out and play, play with confidence, it’s just going — bam, right back in it.”

In the first period Tuesday, Bartkowski fumbled a D-to-D pass from Trotman that led to Minnesota’s first goal. But Bartkowski didn’t get much help from his forwards to slow down the play. When Bartkowski received the pass from Trotman, Thomas Vanek was in his face and in position to strip the puck.

Bartkowski and his blue line mates are not getting much time to start the breakout. Opponents are screaming in on the forecheck and taking away their options. The Bruins aren’t controlling the puck efficiently up the ice and are losing battles along the walls.

This sputtering up-front play prompted coach Claude Julien to change three of his four lines in practice. Marchand started the session with Carl Soderberg and Loui Eriksson. Smith was the fourth-line right wing with Daniel Paille and Gregory Campbell. The only forwards who didn’t change were Lucic, David Krejci, and Seth Griffith, who combined for all three goals against the Wild.

Marchand took an offensive-zone holding penalty just 49 seconds into the third period. Marchand’s penalty (his ninth minor of the year) helped to fuel Minnesota’s rally.

Smith has been even shakier. The right wing is usually a responsible two-way player. But he has been light on his stick in the defensive zone. He hasn’t been good at clearing pucks, especially in battles along the boards. It’s showed at the other end of the ice, where he’s only landed 15 pucks on goal.

Smith’s defensive shortcomings threw off the line’s offensive presence. It was a threesome playing on three different pages. Now it’s Smith’s job to find his efficiency on the fourth line and play his way back up. Smith is like Bartkowski — a young player whose loosening grip on the fundamentals has taken away his confidence.

“A little stronger on the puck,” Smith said of his focus area. “A little bit stronger plays. A lot of things stem from that. When you’re doing that and you’re doing those little things right, your confidence builds and you’re able to make better plays.”

The Bruins have a cupcake on Thursday against the 2-8-0 Sabres. Buffalo is averaging one goal per game. The Sabres were outshot, 37-10, in a 4-0 loss to the Maple Leafs Tuesday. This will be the 5-6-0 Bruins’ chance to get back to .500.

“There’s two things we can control: respecting our structure and our compete level,” Julien said. “If we take those two things, we can survive this. I think that’s what we’ve got to look at right now, those two areas.

“Our compete level wasn’t good enough [Tuesday]. Our structure wasn’t where it should have been on those goals against.

“We just need to understand that no matter who’s in the lineup, it really doesn’t matter. If you play together as a team, respect the structure, and compete hard, you’re giving yourself a chance.”