BATON ROUGE, La. — Already it has congealed into a two-part national ritual. First comes the unveiling of the mid-season rankings from the College Football Playoff Selection Committee, from its command-central boardroom at a surreal hotel with a gaudy atrium near the Dallas-Fort Worth airport. Just after that, there comes, each autumn, like pumpkins on the porch, the hasty reminder that these mid-season rankings have no relevance to anything except the glories of idle chatter because only the final rankings really matter.