(Paul Sancya/Associated Press)

SAN JOSE — The Washington Capitals’ defense hasn’t been healthy since early November, which has caused steady shuffling on a blue line that was stable almost all of last season. No defensive pair has stayed the same outside of the new top pair of Karl Alzner and Matt Niskanen, as John Carlson and Brooks Orpik have missed a combined 61 games and counting.

The rash of injuries and the hope for a long playoff run led the Capitals to acquire defenseman Mike Weber from the Buffalo Sabres before the trade deadline. That means that, even with Carlson out of the lineup for a second time this season, Washington has seven healthy defensemen. Coach Barry Trotz has been rotating Nate Schmidt, Taylor Chorney and Weber in and out of the third pair so no one defenseman gets stale.

“It’s a little bit of opponent and a little bit of trying to give defensemen two games and then maybe switch them out,” Trotz said. “We’re probably keeping four of our guys playing every game and then the other three we’re sort of trying to rotate a little bit. They’ve all played pretty well, and it makes the decision really hard. We try to look at opponents and then try to give them at least two games.”

This new plan has been hardest on Schmidt. In his first full NHL season, the cheery blue-liner has gone from playing on the third pair, and being an occasional healthy scratch, to playing beside Carlson in the top four to moving back to the third pair to now again finding himself out of the lineup on some nights.

“Obviously, the competitive side of you wants to be in every night,” Schmidt said. “But I understand that as a team right now, we’re making sure everyone is available if need be. We have seven guys — and when Carly comes back, eight guys — that can all play, so I think it’s vital to our success if you have everybody kind of on the same page.”

When Carlson recently had to have a procedure for an undisclosed lower-body injury, placed on long-term injured reserve, Orpik and Dmitry Orlov became the team’s second pair and Schmidt shifted to the third pair. The assumption was that Chorney and Weber would rotate in and out of the lineup beside him, but then Schmidt missed two games last week (against the Toronto Maple Leafs and New York Rangers) with a lower-body injury after blocking a shot.

Schmidt was back in the lineup with Weber against the Boston Bruins and played the next game at the Anaheim Ducks, but he was then a healthy scratch for Chorney in Los Angeles. He was back in the lineup against the San Jose Sharks on Saturday. Schmidt said the contusion from the blocked shot is occasionally sore after practice, but he’s no more injured than anyone else at this late point of the season. In other words, that’s not what’s keeping him out of the lineup.

In the 10 games since Orpik has been back, Schmidt has had more than 17 minutes of ice time in a game just once. In the 10 games before that, he had at least 19 minutes seven times. He’s got two goals and 13 assists and is a plus-13 this season.

“Roles changed, especially when John went out,” Schmidt said. “Orly and Brooksie kind of took over where John and I were at. It was different, just getting back to getting used to reduced minutes, but just being able trying to contribute as much as you can in the time you’re given. There’s some things I’d obviously like back, but it wasn’t upset. Sometimes, a couple unlucky bounces here or there, but I thought we were doing pretty well.”

With how the third defensive pair is rotating, does it feel like he, Chorney and Weber are auditioning for who will be the team’s sixth defenseman when Carlson is back?

“Especially with how the year has gone, you try not to feel that way,” Schmidt said. “You try to keep it as professional as possible, especially in the room with these guys because when you really get down to it, we’re all in it to hoist some hardware. As of right now, that’s really the only thing that matters.

“Whether this rotation is what works, or whatever it may be, as long as we get our guys playing their best hockey come playoff time, I guess for me, it really doesn’t matter. We want to do something here, and hopefully, that’ll come to fruition as we get down to the last stretch here of games.”