The salary cap usually prohibits big trades from happening in the NHL but on Friday night, it triggered a blockbuster.

The Colorado Avalanche, in town to play the Bruins, were facing the prospect of Grade A talent Mikko Rantanen going to unrestricted free agency this summer. Presumably not willing to pay Rantanen’s ask that some have reported to be in the neighborhood of $14 million a season, they did something about it.

The Avs sent Rantanen, a two-time 40-goal scorer, to the Carolina Huurricanes for Martin Necas and Jack Drury as well as second and fourth-round picks, while the Chicago Blackhawks acted as the bank, trading Taylor Hall to Carolina for a third-round pick and the Hawks retained 50% of Rantanen’s contract.

For a team that considers itself a Stanley Cup contender like the Avs, it’s a bold move and one that, if they fall short of a Cup, will be endlessly second-guessed. Colorado GM Chris McFarland called it a “bittersweet day” to ship out a homegrown talent that doesn’t appear to make the Avs a better team at the moment.

“These are tough decisions,” said McFarland on Saturday at the Garden. “There’s nothing done in a vacuum. Mikko earned the right to be an unrestricted free agent and he’s five months away from that. You’ve got to make these hard decisions, the player has to make them and the club has to make them and that’s what we did. And getting two cost-controlled assets was important. We felt we got a top six guy and good bottom six guy and away we go.”

It’s the kind of deal that raises the eyebrows of everyone across the league.

“I never know in this league,” said Bruins’ coach Joe Sacco. “I’ve been around it for a long time and you never know. There’s a really good player going one way and a couple of good players coming the other way. Yeah, it always catches you by surprise when you see big name players like that on the move.”

Nikita Zadorov, who play with the Avs and Rantanen for four seasons, was flabbergasted by the trade.

“I was shocked. I was laying in my bed (Friday) night and I never thought Mikko would leave that place. He was a special player for that team, that organization, for the city and everything, so it was kind of a big surprise for me,” said Zadorov. “I thought they would definitely find a way to get a deal done and re-sign and stay there for his whole career. But that’s the part of the game where you never know where you’re going to be the next day. It’s the business side of it. It sucks. I was a little bit speechless, for sure.”

Nathan MacKinnon felt the same way about his long-time teammate.

“I never thought in a million years he would leave. So yeah, it sucks,” said MacKinnon.

The Bruins could well be limited sell mode, depending on how they play between now and the March 7 deadline. The meager return that Chicago got for Hall while also doing Carolina the favor of facilitating the deal makes you wonder just how much the B’s would get for their movable assets. If the team slides out of the playoff picture, B’s management can only hope that Chicago misread the market and simply made a bad deal.

Despite all the speculation surrounding his team, Sacco doesn’t think uneasiness has set in.

“I don’t think right now that that’s a concern for anyone or that it’s creeping into our heads. We’re human, right, and everybody has things going on,” said Sacco. “But we have six or seven games before the extended break and that’s where our focus is right now. Not to get ahead of ourselves, but that’s what we’re looking at. But it’s our job, my job to make sure we do that, stay focused on the task at hand that’s in front of us. We can’t worry about what’s going on down the road.”

Big kills

The Bruins came up with two big penalty kills, the first of which gave them the momentum to finally manufacture some offense in the third period in the 3-1 win over the Avs.

The B’s are currently ranked 24th in the PK, but they are much better on the kill at home than they are on the road, where they’re ranked dead last.

“I think our kill has been good this year. I mean, if you look at the numbers, yeah, but we either give up three or we give up zero. It’s never one or two goals. I think when we’re really dialed in on the details, when we know our spots, when we know where to put our sticks, when we prepare ourselves better for the game plan, I think that’s when we succeed on the kill,” said Zadorov.

Loose pucks

Elias Lindholm has not contributed much offense this season, but he did have a big day on the dot, winning 14-of-17 faceoffs. … Bruins are next back in action on Tuesday in Buffalo.