It would not be entirely accurate to say Milan Lucic is the most important player on the Bruins, the individual key to the success or failure of the group. But he’s on a pretty short list of core guys who have to be in good form for this team to be a championship contender. The fact so many of those core players have been subpar for lengthy stretches of this season is the reason so many games have been low-scoring, inconsistent struggles for the Bruins. Yes, they’ve found ways to grind out wins most nights. But the B’s have not been looking like a team poised, a month from now, to compete for the Stanley Cup. So the best news of last night’s sorely needed 3-2 shootout win against the upstart Toronto Maple Leafs at the Garden was that Lucic looked like Lucic — the genuine item, not the version that had gone 15 games without a goal — and provided a critical spark that jump-started the team. The Bruins were again playing uninspired hockey in the first period and into the second, trailing the Maple Leafs, 2-0. Coach Claude Julien would admit following the win that the team’s every-other-night schedule has made it tired and “heavy,” lacking energy. But 9:49 into the second period, Lucic turned on the jets to blow around Toronto defenseman Cody Franson just inside the offensive zone, walk in alone and beat goalie James Reimer with a 5-hole forehander for just his fifth goal of the season. And just like that the Bruins — and Lucic — woke up. “It was starting to get really frustrating going as long as I did without a goal,” said Lucic, who had lost his spot on what is ostensibly the No. 1 line, getting dropped to the third line at practice Sunday. Losing his spot on the line with David Krejci and Nathan Horton, Lucic found himself skating with Rich Peverley and Jordan Caron. The shakeup of lines was one way for Julien to try to snap the club out of its recent funk. And Lucic out of his.