All three players are reputed for their abilities to finish their checks and being extremely difficult to play against, something Prust said was a priority for the new men in charge in Montreal.
"It's good for a team's identity to have a bit of team toughness," Prust told reporters in a conference call. "When other teams come into our building, they need to know they're going to be in for a long night."
Prust, 28, signed a four-year deal worth $10 million after excelling last season as a key penalty killer and physical, checking forward with the New York Rangers. That is a considerable raise from the $800,000 Prust earned the past two years with the Rangers.
2012 FREE AGENCY
Free agency previews (by division)
With free agency opening Sunday at noon ET, NHL.com takes a look at the needs of all 30 teams -- division by division -- as well as the Top 10 free agents in each division:
Prust played 82 games in each of the past two seasons with the Rangers, compiling 18 goals, 28 assists and 316 penalty minutes.
But he said it quickly became clear he would not be back in Manhattan next season.
"When the season ended, I thought there was a high chance we’d get a deal done," Prust said, adding he spoke to coach John Tortorella on Sunday and that his agent spoke with general manager Glen Sather. "But that changed in the last little while and I started to understand maybe my time was done as a Ranger."
Prust said New York's interest in retaining him "wasn't anywhere close to where Montreal was."
He said he spoke with Bergevin, Therrien and director of player personnel Scott Mellanby before signing with the Canadiens, and he likes the wind of change that is blowing through Montreal with the new regime in the front office and behind the bench.
"The changes that are happening, I think are great, and I just wanted to be a part of that change and turning this thing around," Prust said. "I think they're lacking someone like me in their lineup."
Prust noted that with rugged forwards Travis Moen and Ryan White returning and Sunday's addition of Armstrong, the Canadiens are adding players who fit Therrien's and Bergevin's stated philosophies that an NHL team needs different types of talents in order to excel.
"I know [Therrien] likes players like that and he believes you need players like that to be successful. You can't just have a team full of skill guys," Prust said. "That's the one thing I really wanted to hear."
Bergevin was originally supposed to address the media Sunday, but finally decided to hold off until Monday afternoon. He still has a hole to fill as the Canadiens need a top-six left wing who could play opposite team captain Brian Gionta on a potential line with Tomas Plekanec. Names like Jaromir Jagr – who has a close relationship with Plekanec – and Shane Doan remain on the market and may intrigue the Canadiens GM.
Both Armstrong and Bouillon have histories with Therrien that surely played in their favor Sunday.
Armstrong was bought out of the final year of his $3 million contract by the Toronto Maple Leafs on Saturday and signed a one-year deal worth a reported $1 million, which matches the amount he lost when he was bought out.
Armstrong played for three-and-a-half seasons under Therrien with Pittsburgh's minor-league affiliate, the Wilkes-Barre/Scranton Penguins of the American Hockey League from 2003-06. When Therrien was promoted to the Penguins during the 2005-06 season, Armstrong quickly followed, playing for him until he was traded to Atlanta as part of the deal that brought Marian Hossa to Pittsburgh.
Right Wing - MTL
GOALS: 1 | ASST: 2 | PTS: 3
SOG: 14 | +/-: -8
"He knows how I play, he knows what I can do and he knows how to get the most out of me," Armstrong told RDS. "I really believe that, so it didn't take long. I wanted to go there."
Armstrong told TSN he's been a Canadiens fan since he was a youngster.
"I was a member of the Montreal Canadiens fan club as a kid," Armstrong said. "I think I was the only member in Saskatoon."
Armstrong has had trouble with injuries the past two years in Toronto with a list of ailments that included a broken nose, broken foot, tendon problem in a finger, concussion, badly sprained ankle and a bout with blurred vision and dizziness.
He played just 79 games the past two seasons combined, and was told by the Maple Leafs he would be unable to bounce back. Armstrong will now have six opportunities a year to prove the Leafs wrong.
"The last two years have been difficult injury-wise, dealing with what I think was a bit of bad luck," Armstrong told RDS. "When you get bought out and the management there doesn't think you can do it anymore, it motivates you and pushes you. So obviously, when you play your old team it adds a little fire to the oven."
Bouillon spent the past three seasons with the Nashville Predators and will be able to rekindle his relationship with Therrien in Montreal after signing a one-year contract for $1.5 million. Bouillon played his final three seasons in the Quebec Major Junior Hockey League under Therrien, then played under him in the AHL before following him to the NHL In Montreal, where he played for nine seasons.
"Michel helped me in junior, he helped me in the AHL and he gave me my shot to make the NHL in Montreal," Bouillon told RDS. "I was probably one of the most excited players when he got the job in Montreal, and my arrival today is largely because of him."
A rugged defenseman who plays bigger than his 5-foot-8, 200-pound frame, Bouillon provides depth to a defense group that was ravaged by injury last season and he likely will need to fight for a spot on Montreal's third pairing.
But more importantly, Bouillon's game is defined by his toughness, his willingness to challenge any opponent no matter his size, and how difficult he can make the lives of the players wearing a different colored jersey.
And in that sense, he fits right in with what Bergevin apparently wanted to accomplish on Day One of free agency.