In every league there are several teams whose fan base is so rabid and widespread that all of their games sellout or come close, television ratings are through the roof, and merchandise sales are astronomical. Usually these teams have years of success, years of tradition, and that tradition has been carried out through generations within families. The Toronto Maple Leafs. The New York Yankees. The Dallas Cowboys. The Los Angeles Lakers.
But it's not enough just to sell all the tickets and put the games on television. Marketing departments of these teams should be working more than any other team. You can't rely on the game experience to captivate fans, so yo have to find other ways and be more creative to satisfy your fans around the world. That means scheduling off-season caravans: having players and management tour throughout the region of fans, meeting those that can't afford to come to games, but who watch every game despite being miles away. Making merchandise available to these people: if all of New England is Red Sox nation (and likely more than that), the Sox must have merchandise stores in Vermont, New Hampshire, Maine. Have a presence in every mall across the region.
Team practices and skills competitions are great ways to get fans out to the stadium or arena without it costing them very much. Schedule game viewings in local movie theatres, charity events in local communities. Even a "greatest [team] town" where fans in the community rally to show that they are the best town's fans of their team. These are all ways that you keep fans active and engaged in the team without being able to come to the stadium and show their support that way. Locating minor league operations in adjoining towns are also fantastic, bigger scale ways of keeping fans involved.
Being able to do that, and finding alternate ways of keeping fans interest in the game will help the truly dark ages of a franchise. The Cubs and Leafs have both fielded unsuccessful teams for decades, yet their fan commitment remains some of the highest in professional sports. Marketers have been able to capitalize on the tradition of the team and maintained their off field success. Imagine the outpouring of support when one of those teams eventually wins a championship.
