The two have been a fixture on Washington's blue line, and neither has missed a game over the past three seasons. But after roughly five seasons of playing on the same defensive pair, Carlson and Alzner may not be as synonymous with the Capitals as they are with each other.
"[People] always ask me, 'What are you guys going to do together today? Where did you guys go eat on the road together?'" Alzner told NHL.com. "If they were talking to me, they would ask about him. If they were talking to him, they would ask about me. It was pretty weird. You start thinking, 'Is this going to happen for the next 10 years?' It's really strange."
Remarkably, after years as Washington's go-to defensive pairing, it was the duo being split that has helped propel the streaking Capitals, who lead the New York Rangers 2-1 in their Eastern Conference Quarterfinals series.
From the moment the two blueliners were paired together, they've had tremendous success in the Capitals' organization -- winning a 2009 Calder Cup championship with Hershey of the American Hockey League then a Presidents' Trophy with Washington the following season, their first in the NHL.
Carlson, 23, and Alzner, 24, enjoyed a career's worth of success in barely two seasons. Through it all, the pair developed a strong rapport with each other as well as with Mathieu Perreault and Michal Neuvirth, teammates who also were members of that championship squad in Hershey.
"It's just getting lucky and being in a good organization. You still have to play the game. Now we've built ourselves up to here," Carlson said prior to Game 3 against the Rangers on Monday. "I find myself really close to those guys. Probably because of that [success]."
But after three full seasons together before 2012-13, the duo suddenly experienced something they never had confronted in their brief professional careers: losing. Washington started 2-7-1, causing a panic among Capitals faithful that the team might miss the Stanley Cup Playoffs for the first time since 2007.
"A lot of us have not been on teams that have lost a whole lot," Alzner said. "Being so far under .500, second-last in the League, that's a really scary feeling. Especially in a shortened season. How the heck are you going to climb out of that hole? We all felt we should have been at the top of the League and we weren't there."
The team has been red-hot over the past two months. The Capitals opened April with eight straight wins and closed the season on a 15-2-2 tear. Oddly enough, it was the decision to separate Carlson and Alzner that precipitated the remarkable turnaround.
"It was weird at first, just because we're so comfortable with each other," Alzner said. "Then when you change it, it sets you back. You have to start working at it again and create a new chemistry. At the same time, we knew it was the right move. We weren't too bitter about it. It ended up working pretty good for us. Obviously I'd like to play with him again at some point, but I wasn't pouting about it."
It seemed unusual that Washington's most prominent duo since Obama and Biden suddenly would be split. The two first-round picks lived together at one point and seemed to complement each other perfectly on the ice, with Carlson playing the aggressive puck-mover and Alzner playing the more conservative, stay-at-home role. But the move was warranted.
In a 4-2 loss to the Winnipeg Jets on Jan. 22, Alzner was on the ice for three Jets goals and Carlson was on for two. On Jan. 24 the pair was on the ice for all four goals in a 4-1 loss to the Montreal Canadiens. The following night, Carlson was on for all three goals in a 3-2 overtime loss to the New Jersey Devils.
"I like to play a shut-down role," Alzner said. "[Carlson], as well as playing an offensive role, he plays a shut-down role. Splitting ourselves, we get a little of both on two different units."
The results have been hard to argue with. Not only has Carlson's point production increased slightly this season, but his plus-11 rating in the regular season was a far from last season's minus-15, and even more impressive considering he sported an even rating at the beginning of March. And the Washington defense has been airtight, allowing two goals or fewer in nine of the past 12 regular-season and playoff games.
It's quite a turnaround for a team that sat last in the Eastern Conference on Feb. 17 and was allowing more than four goals per game.
If anything, the Carlson-Alzner split may have aided the development of both players. That evolution should prove key if the Capitals want to make an extended playoff run.
"I think we've done a good job of learning every year," Carlson said. "That's what you look for, just getting better every season. Obviously that's our goal. I think we've done a good job of that."