It's the way the Senators defenseman, now 6 feet, 191 pounds, has taken on everyone and everything, grabbing hold of a team and a dressing room and these Stanley Cup Playoffs, a captain finding his voice and his stride and becoming the best player playing right now -- arguably the best player in the NHL.
Not just the best defenseman. The best player.
They have run out of things to say. They have used all the ways -- new and old, original and cliché -- of explaining Karlsson. Because there is no explaining Karlsson, particularly what the 26-year-old is doing at this moment, so much so that his 14 points (two goals, 12 assists) in 15 playoff games don't begin to demonstrate his impact. He is carrying his Senators, and doing it all while hobbled by two hairline fractures in his left heel.
No wonder they have no words left. Still, they try.
"He's been great," forward Clarke MacArthur said. "You see the way he's bought into the intangibles this year, shot-blocking, the Norris [Trophy] talk. When you're in our room it's a no-brainer who the best player in the world is. We know it."
Video: Erik Karlsson joins Billy Jaffe one on one
When Dorion sat with Guy Boucher for the first part of his interview last year, before he was hired as coach, there was significant talk of Karlsson, of how Boucher would handle him.
Boucher was convinced that Karlsson, who has often been dogged by the reputation that his defense does not match up to his offense, could improve defensively. He believed this was a player who should play on the penalty kill, who should be counted on in the final minutes of games, who should be among the League leaders in blocked shots.
"It wasn't because he wasn't good," Boucher said of the defensive issues. "I thought he was a great stick-on-puck guy. I thought he had terrific gap [spacing]. But the energy he was spending on the ice prevented him from being just as good defensively. It wasn't because he didn't have the tools."
And that was how it came to be that Karlsson was on the ice the final crucial minutes of Game 6 of the Eastern Conference Second Round against the New York Rangers, with the Senators leading by one goal.
"I think that tells you something: If you would have asked a lot of people at the end of last year, 'Erik's going to play almost six out of the last eight minutes in a one-goal game,' I don't think a lot of people would have believed you," Dorion said. "But we saw how good he was in those last eight minutes."
That was the game that got Ottawa to the Eastern Conference Final, for the first time in a decade, to Game 4 against the Pittsburgh Penguins on Friday (8 p.m. ET; NBCSN, CBC, TVA Sports) here, with the Senators leading the best-of-7 series 2-1.
But what got Karlsson here?
It would seem to be nearly impossible for a player at the level of Karlsson to make the jump he has made this season, to become a better player than the one who won two of the past five Norris Trophies, who established himself as one of the premier defensemen in the NHL.
And yet, he has, responding to the system put in place by Boucher, the 1-3-1, by adapting to shorter shifts and more defensive responsibility. He has done it by accepting help, sharing a load that would not be easy on anyone.
"Probably the person that has helped the most is Daniel Alfredsson," Dorion said of the Senators legend who captained them for 13 seasons and is their senior adviser of hockey operations.
Alfredsson, after all, is the one person who knows what it's like to be Karlsson, to be a captain in Ottawa, to lead this team to these heights. They've played side by side, both with the Senators and with Sweden, and have dealt with the same position and pressures.
Video: OTT@NYR, Gm6: Karlsson buries Ryan's slick dish
He has not been the only one, though, who has taken on some of the burden. Defenseman Dion Phaneuf, the former Toronto Maple Leafs captain, was placed next to Karlsson in the dressing room, and the two hit it off almost immediately. They have taken trips together, played golf, become a tandem.
As Boucher said, Phaneuf has been "great for Erik, deflecting a lot of the pressure."
"I think that from knowing what he has to deal with, and being a captain, there's a lot of things that people don't know that go with it," Phaneuf said. "There's a lot of responsibility and a lot on your shoulders. For me, I try to support him in any way I can. It's about sharing the responsibility of leadership."
Ultimately, though, it's on Karlsson. He calls teammates out and explains their successes and their failures, as he continues to learn and mature and find his voice in his third season as captain.
That could be seen in Game 2 of the Eastern Conference First Round against the Boston Bruins, when Karlsson lit into forward Derick Brassard after a miscue ended in a shorthanded goal for the Bruins. He screamed at his teammate, the same one he would later set up with an eye-popping pass for the tying goal in the Senators win.
"He expects it every night," forward Bobby Ryan said. "He expects the best out of himself and then he demands the best out of everybody around him. That's why he's our leader and that's why he's the best in the world."
Karlsson wasn't happy. He believed he deserved the Norris Trophy after the 2015-2016 season, an honor that went to Drew Doughty of the Los Angeles Kings, even after Karlsson had 82 points in 82 games, including a League-leading 66 assists.
"I wouldn't say he took it hard, but he thought he was probably the best defenseman last year and not getting the Norris, I remember talking to him -- it's not just about points, it's about playing to the best of your ability at that position," Dorion said.
So Karlsson became better.
"I think that that's one of my goals every year is trying to develop as an individual and as a player," Karlsson said. "I think that this year we have taken good strides forward, not only me, but the whole organization and everybody on our team, and I think that that has helped me turn into a better player than I was before."
That is inarguable.
"What I like is that Erik has taken all the aspects of a premier player to another level," Boucher said. "He's always had that offense, he's always had that vision, he's always had that skill, but what he's done this year is he's used it in the right moments for the right reasons."
Video: The guys breakdown Erik Karlsson's clutch play
He has grabbed the Senators and brought them along with him, becoming a face of the NHL and the future of the NHL all at the same time.
"The game is much faster today, and it's going to be faster 10 years from now, too," said Peter Popovic, a former NHL defenseman and a Team Sweden assistant at the World Cup of Hockey 2016. "Erik, he's got speed in his legs, but he's got speed in his hands and in his head, too. I think the best players in the world, it doesn't matter if they play defense or forward, I think they're a half-step ahead of everybody."
This is Erik Karlsson.
This is his team. This is his year. This is his NHL, a league that is moving forward in the direction of players like him, of speed and skill and push. He has everything he needs, and everywhere to go.