All it took was one pretty good game to underscore just how valuable Brad Marchand is to the Bruins when he’s mentally, physically and emotionally invested into what’s going on around him. All three parts were on display in the 4-1 victory over the moribund Florida Panthers at TD Garden on Thursday night. It showed how free and easy things can be for the B’s agitator when he brushes that monkey off his back. Sure, it ended with a third-period goal that ended up as the game-winner while snapping a 12-game goal-scoring drought. “I think [Marchand] scored the goal the way we know he scores,” said coach Claude Julien. “Made a great play at the blue line, and then just skated to the net. [He] was able to jump on that loose puck. He talked about moving his feet, and when he moves his feet he creates things and he scores himself some goals too.” It all started in the first period when Marchand was front and center attempting to inspire himself and his teammates. Marchand had to get dragged back to the Boston bench by linesman Darren Gibbs as he yapped and chirped with a group of Florida players around the Panthers net, and kept going back for more. It was particularly noticeable as a rare show of anything remarkable – along with the Gregory Campbell scrap with Jesse Winchester standing up for an elbow to Chris Kelly’s head -- in the sleepy first 20 minutes for the Black and Gold. For Marchand it was a positive sign when far too many times he’s stayed out of the fray rather than dropping himself right into the emotional furnace burning in the danger areas of the ice. “It’s frustrating, you want to contribute all you can. When you see the games go by and not only you’re not scoring, but I wasn’t really playing really well,” said Marchand. “It’s very frustrating. You want to pull your own weight especially with the team we have. Everyone is expected to play up to par and so like I said, it was nice to get one and just got to keep trying to build.” That willingness to throw himself into the trouble areas on the ice is also exactly what led him to his goal. Marchand had made a high-end play to carry the puck into the offensive zone rather than simply dump the puck deep, and then crashed the net when the puck shot toward the net from Dennis Seidenberg’s left point. The German defenseman’s shot trickled through the pads of Scott Clemmensen, and Marchand pounced on the loose puck in the crease before tapping it in.