Both moves have proved important to the Canadiens, who missed the playoffs last season after having had the best record in the N.H.L. at the end of November. They defeated the Devils on Thursday night and again hold the best record in the league, at 18-6-3.

Joining Montreal has afforded a measure of redemption for Radulov, who left the N.H.L. twice in the past eight years, each time with his reputation in tatters.

“I never put an end to my N.H.L. career,” Radulov said. “I always wanted to come back.”

The province of Quebec is an apropos destination for Radulov. As a teenager, he starred with the Quebec Remparts of the Quebec Major Junior Hockey League. After carrying the Remparts to the 2006 Memorial Cup, Canadian junior hockey’s grandest prize, Radulov was hailed as a hero in the province.

Angelo Esposito, a former Remparts teammate of Radulov’s, said: “The fans loved him. He was kind of all over the place, bouncing off the walls. He had so much energy, but it’s a positive energy.”

That energy proved problematic when Radulov joined the Predators, who picked him 15th over all in the 2004 draft. From the moment he arrived in 2006, Radulov showed great talent and little maturity. Barry Trotz, Nashville’s coach at the time, allocated several hours for private meetings to help mentor Radulov. Still, harnessing the young Russian’s focus proved difficult.