The end had seemed near so many times throughout Claude Julien's years with the Boston Bruins. That was why, when the Bruins fired him one year ago, on Feb. 7, 2017, it was both a complete surprise and not at all a surprise.

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But, in his 10th season with the Bruins, it was time for a change, even for a team that had been to the Stanley Cup Final twice and won the Cup during his tenure.

The change came in the form of Bruce Cassidy.

It was, perhaps, exactly the right move at exactly the right time.

This was the moment when the Bruins committed to a new generation, though they have retained some players from their previous incarnation, which won the Cup in 2011. But that group, including forwards Patrice Bergeron, Brad Marchand and David Krejci, and defenseman Zdeno Chara, needed some new blood.

Fortunately, there was young talent ready to break through, and it has this season, forced partly by the growth and development of the Bruins' drafted players, partly by a series of injuries that led them to rely on rookies: defensemen Charlie McAvoy and Matt Grzelcyk, and forwards Jake DeBrusk, Danton Heinen and Anders Bjork.

And Cassidy's strengths lie in coaching that young talent. That is where it has come together for Boston.

"I think the coaching staff in general, but Bruce obviously as our head coach, [he] came from a development league in the American Hockey League and knows the ups and downs," Bruins president Cam Neely said. "I think for here it's also developing and teaching. And I think that's what our staff really focused on and knew that they would have to do, especially early in the season when we had all those injuries."

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This was not only what Cassidy was positioned to do. It was what he thrived on, teaching, developing, getting players to find their games as they moved up the rungs of the hockey world.

"For younger guys he's [in] more of a teaching role and he'll let you know when you make a mistake, but he's trying to show you how you can improve on that," forward Noel Acciari said. "Being able to play for him down in Providence and just knowing how he coaches and playing for him up here, nothing much has changed with him. If you give him everything you have, he's not going to complain. You might make your mistakes -- he knows everyone's not perfect, and he's just looking to correct some stuff here and there. But I enjoy playing for him and I know a lot of guys do too."

The marriage has worked.

After Cassidy replaced Julien, the Bruins went 18-8-1 and got knocked out of the Stanley Cup Playoffs in the Eastern Conference First Round by the Ottawa Senators in six games with several injured defensemen. What Cassidy has done with a full season to tutor his pupils has been remarkable.

This season, he has molded the Bruins, thought to be a bubble playoff team, into the hottest team in the NHL. The Bruins, who won 3-2 at the Detroit Red Wings on Tuesday, are 20-2-4 in their past 26 games and 26-4-4 in their past 34 heading into their game at the New York Rangers on Wednesday (8 p.m. ET; NBCSN, NHL.TV).

If not for Gerard Gallant, who has coached the expansion Vegas Golden Knights to the top of the Western Conference, Cassidy could be the favorite for the Jack Adams Award.

That is impressive for someone who had not been an NHL coach for more than a decade, since his stint with the Washington Capitals ended 28 games into 2003-04, his second season. He was 47-47-9 in Washington.

"I'm a much different person than I was 15 years ago in Washington, and I'm much more comfortable in my skin than I was as an NHL coach back then," Cassidy, who is 50-19-9 with the Bruins, said Tuesday. "The game itself has changed so much since then that I've had to evolve with it.

"I think the biggest thing in the last year is that we're constantly trying to perfect the way we play. We want to be a difficult team to play against while still being aggressive offensively, and we are always working to get that balance right. We're getting closer all the time, but there are times where things go wrong and we have to fix them."

And he has had the ability to do that. Part of that has come from having spent the past 10 seasons in the organization, starting in 2008 as a Providence assistant before becoming coach in 2011. He became an assistant under Julien in 2016-2017.

"I was a familiar face when I took over," Cassidy said. "I had coached a lot of our younger guys and while I hadn't coached guys like [Bergeron] and [Chara], they knew me. I think that helped build a trust factor quite quickly."

They trust him. He trusts them. And, faster than anyone thought, they are among the NHL's elite; Boston is fourth in the League in points (72), behind the Tampa Bay Lightning (75), Golden Knights (74), and Winnipeg Jets (73), with at least two games in hand on each of them.

"It's been a fun year," Cassidy said, "and I hope it keeps going."

NHL.com correspondent Dave Hogg contributed to this report

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