Michel Therrien is back at it again.

After a tightly-contested first two periods against the Columbus Blue Jackets Tuesday night, Montreal Canadiens head coach Michel Therrien decided to shuffle the lines heading into the third period. It seemed to work, as the Habs scored a late power play goal to squeeze out a 2-1 victory over the lowly Blue Jackets to kick off December.

In his postgame press conference, the Canadiens’ coach said he liked what he saw from the new-look lines.

“I wanted to bring something different — something new — to the Desharnais and Plekanec line,” said Therrien. “I believe they gave us a lot of life. I really like the way Pac responded playing with Davey, and I really liked the way Flash played with Pleky. I enjoyed how the guys were reacting to the changes.”

He enjoyed it so much that, according to TSN’s John Lu, those same line combinations were back together at practice in preparation for Montreal’s next game against the Washington Capitals Thursday night.

#Habs practice lines: Pacioretty-Desharnais-Weise Fleischmann-Plekanec-Byron Eller-Galchenyuk-Andrighetto/Semin DSP – Flynn – Thomas Carr

— John Lu (@JohnLuTSNMtl) December 2, 2015

The injury bug has hit the Canadiens hard over the last couple of weeks, with Carey Price, Brendan Gallagher, Alexander Semin and Torrey Mitchell on the shelf for extended periods of time. And naturally, with injuries come lineup changes; there’s really no way around that.

With that said, the Habs’ 2015-16 possession numbers are better than they have been in years. They’re generating more chances, killing opponents with speed and scoring goals in bunches. While it’s understandable for a coach to occasionally switch up the lines, the idea of reverting back to an old experiment — one that hasn’t panned out in the past — doesn’t make much sense. Yet here we are, two months into the season, and Therrien’s favorite trio is back together again.

Here’s why reuniting the Pacioretty-Desharnais-Weise line is a mistake.

Pacioretty and Desharnais Don’t Need Each Other

They really don’t.

David Desharnais will never be a first-line center. Saddling him with that task not only brings down his linemates, but limits Desharnais’ ceiling. Michel Therrien insists on making it happen, but the reality is, when the diminutive center faces elite-level competition — names like Jonathan Toews, Anze Kopitar, Nicklas Backstrom and Patrice Bergeron come to mind — he gets eaten alive. He’s simply not equipped to handle the demands of being a No. 1 center, and expecting him to do so is unfair.

Since his demotion to the third line this season, No. 51’s offensive production has taken a big jump — from 1.64 points per 60 minutes to 2.23 points per 60 minutes at even strength. Desharnais is taking advantage of his role change and exposing low-quality competition with his quickness and playmaking ability. His possession numbers have been stagnant, but because he’s been up against bottom-six forwards, his mediocre defensive game hasn’t hampered his success at even strength.

On the other hand, Max Pacioretty has seen his game take a giant leap forward this season. Not only is the 27-year-old on pace for a career-high 41 goals, but the underlying statistics suggest Pacioretty is playing much better at both ends of the ice.

Even though Pacioretty’s SCF60 (scoring chances for per 60 minutes) at even strength took a minor hit this season, it’s proving to be well worth the sacrifice. In 2014-15, Pacioretty was allowing nearly 28 scoring chances against per 60 minutes at even strength. That number has dropped to just over 24. His possession numbers are way up, and he’s playing a more sound 200-foot game.

At the same time, the left-winger’s offensive game really hasn’t taken much of a dive. Pacioretty is still getting to high-danger areas of the ice and giving goalies nightmares with his laser snipe shot and terrific speed. According to DTM About Heart, Pacioretty ranks second in the league in ixG (expected goals) among forwards, ahead of Alexander Ovechkin, Vladimir Tarasenko and Corey Perry. He also leads the team with 71 shots on goal at even strength and is the second-best possession-driving forward on the team — Gallagher leads the Canadiens with a 56.64 CF%.

Both Pacioretty and Desharnais have actually improved without each other, and while they each serve an important role, that role should not include playing on the first line together.

There’s another reason this line should not be reunited, though, and it has to do with the guy on the right side.

Dale Weise: The Possession Drag

Since coming to Montreal in a trade for Raphael Diaz, Dale Weise has quickly become a favorite among Canadiens fans, and for good reason. Weise loves being a Hab and plays his heart out every time he steps onto the ice. His work ethic and drive to help his team win at all costs are assets any team would love to have. But for all the hard work and determination, Weise is not a top-six forward, and inserting him on the top line would be a mistake.

This would not be the first time the former Vancouver Canuck plays on the first trio. Weise saw significant minutes with Pacioretty and Desharnais in 2014-15, and there were flashes of brilliance on his part, but, overall, the experiment failed.

(Marilyn Indahl-USA TODAY Sports)

Last season, Weise was among the least effective possession drivers on the team. There were only two players he actually had a positive impact on — Desharnais and Manny Malhotra.

Therrien got it right when he opted to put Weise with Desharnais to start 2015-16, as the two seem to have some chemistry. However, Weise was a major possession drag on Pacioretty last year, and one can only assume he would only hold Pacioretty back if the two continue to play together this season.

Weise serves a purpose and deserves every bit of the praise he’s gotten so far this season. He’s more than exceeded expectations for a third-liner. But that’s just it — he’s a third-liner. Weise doesn’t have the offensive instincts to play a top-six role, nor the defensive acumen to go against the opponent’s best players. Moving him to the first line would only bring a player like Pacioretty down and ultimately hurt the team’s long-term success.

Final Thoughts

There was no need to change what was working. The third line was clicking and the first line was doing first-line things.

While the injury to Brendan Gallagher was a tough pill to swallow, continuing to find a temporary band-aid within the Canadiens’ system is not the end of the world. It’s obvious Devante Smith-Pelly was not the answer, but the Habs should be exhausting all options on the right side before reverting back to their old line combinations.

Now is not the time to be experimenting with past failures, especially with a rookie goaltender in net.