There was a motivational quote written on the white board in the visitors’ locker room that was attributed to star forward Jaylen Brown, although he didn’t think that he actually uttered those particular words. “Whatever it takes to inspire the team,” Brown said. Brown did, however, cite one of his favorite sayings that he believes applies to Boston’s relative struggles this season: “Winter always turns to spring.” In this case, the saying reflects Brown’s confidence that the Celtics will soon go on a dominant run. Boston hasn’t had a winning streak longer than three games since November. “It’s coming. It’s coming,” said Brown, who had 22 points, 8 rebounds and 6 assists against the Mavs. “You just keep working. It’s coming. You got to keep fighting if you want to be what you say you want to be, got to be tested and you got to pass those tests and be worthy of it. It’s been hard. Shots are not going in. It’s looked a little bit ugly at times. Our offense has been a little bit [off]. The energy hasn’t been flowing the way it’s used to, but that’s all right.