The Montreal Canadiens have made their second gigantic move in the last year, with general manager Marc Bergevin deciding that the time was right to move on from head coach Michel Therrien after over four years with the team. Bergevin capitalized on the Boston Bruins' firing of Claude Julien to bring in a coach that checks all the necessary boxes for Montreal, and happens to be one of the game's five best at his job.
Oddly enough, this is the second time Julien has replaced Therrien as head coach of the Canadiens—the first being in 2003—and the team got significantly better when it originally happened. While a significant improvement might not show up in the standings this time around, as the Canadiens are a first-place team in the Atlantic, this is a move that's a big positive for a Habs club with Stanley Cup aspirations.
While shot attempts weren't publicly available to generate Corsi numbers to evaluate a team's play at even strength back when Julien first replaced Therrien, a few years ago Benjamin Wendorf—one of the original voices of the hockey analytics movement—used shots on goal through the first two periods to estimate possession control.
Using that data, Wendorf looked at midseason coaching changes further back than 2007-08 when Corsi became easily trackable, and one of the names that jumped out at him was… Michel Therrien.
As it turns out, Therrien was one of the few coaches who had a consistently negative impact on team performance compared to who he was replacing, or being replaced by, with the exception of taking over in Pittsburgh for Ed Olczyk, who is arguably one of the worst coaches ever.
The last time Julien specifically took over for Therrien, he improved the Canadiens from controlling about 41.9 percent of possession to roughly 47 percent. Julien wasn't able to bring the Canadiens into the positives that season, but it was also not the best roster, so we shouldn't read too much into that.
Nowadays, Therrien is nowhere close to as inept of a coach as he was in his first run with the Habs, where he was inarguably terrible. Therrien had several seasons during this most recent run that wouldn't be described as great, but he was clearly showing overall improvements as a coach.
That means it's probably unlikely that the Canadiens, who are the fourth-best score-adjusted Corsi team in the NHL this season at 52.85 percent, will see a five-point improvement there, though in all likelihood they will notice an upgrade, if we look at the history of both coaches.
Over the last 10 seasons, Julien has only been below even in score-adjusted possession once, while Therrien has been below average four of his seven seasons. In the seven seasons both coaches have been active in the NHL at the same time, Therrien's team has only ever outperformed Julien's club once.
In fact, in Julien's tenure with the Bruins, they generated the second-most shot attempts per 60 minutes of any team, and allowed the sixth-least shot attempts against. In contrast, during Therrien's tenure in Montreal, the Canadiens generated the 10th-most shot attempts for in the league, and allowed the 11th-most shot attempts against.
One of those is OK, and one is a recipe for long-term success—Julien has a Stanley Cup ring to prove it.
What's going to be challenging for Julien in Montreal will be adjusting his system to a team that isn't built around the centre position. The Canadiens don't have a Patrice Bergeron or David Krejci, though you could argue that Alex Galchenyuk is equal to the task of being the Habs' Krejci, which still leaves Julien without a generational two-way centre.
The Canadiens' strengths are on the wings, where they have six strong possession drivers in Max Pacioretty, Alex Radulov, Artturi Lehkonen, Brendan Gallagher, Andrew Shaw, and Paul Byron. That's not a typical setup for a successful team, but it does allow the Canadiens to insulate their relatively weak centre line.
The Canadiens also have two defencemen on the right side in Shea Weber and Jeff Petry who are better than any of Boston's defensive corps at the moment, which gives Julien some options there.
While the teams are structured differently, you'd likely find a general consensus that the Canadiens' roster is superior to the Bruins right now. And yet, under Julien, the Bruins had the highest expected goals for percentage in the NHL at even strength and in all situations this year, according to Corsica Hockey.
Julien's coaching career has been so successful that it's difficult to find a negative spin on this move—it's the first time in a while that the Canadiens can boast having one of the top coaches in the NHL, and it comes at a time when they absolutely have to win.