NASHVILLE, Tenn. — Nathan MacKinnon finally scored his first goal of the season, getting a lucky bounce off a Nashville Predators defender to give the Avalanche the early lead Tuesday at Bridgestone Arena. It was the kind of bounce MacKinnon said would get him going in the goal-scoring department. But it was all downhill from there for the Avs, who lost their composure and fell 4-1 to the defending Western Conference champions. “Just bad reads.