A stroke of genius? A cry for help? An insult to English teachers? Whatever else it is, the A-League's new marketing slogan, "You've gotta have a team", is as well-struck and accurate as Tim Cahill's first goal for Melbourne City, hitting precisely where the league has fallen short and where it needs to go.

Team loyalty is the magic dust for any sporting competition. The statement "I follow the AFL, but I don't have a team" is enough to get you run out of Melbourne. It's why you always see someone in a Richmond Tigers guernsey on the roadside of the Tour de France; why sunburnt flag-wavers in yellow shirts will travel to Abu Dhabi to watch Australia play cricket; why there are hangovers down Cronulla way that haven't even got started yet.

But there's a difference between "You've gotta have a team" and the old NRL slogan "That's my team" (produced under David Gallop's stewardship of that code). The NRL version, presuming fans already had a team, aimed to reboot existing and lapsed loyalties. The A-League, which is only 12 years old and challenged to hit top speed from a standing start, sees that its next step must lie in converting general, vague, wafty interest into frothing tribal commitment. You can't just like Besart Berisha and follow whichever team he's playing for. You can't tune in to watch Aaron Mooy when he's at the Wanderers and then at Melbourne City (and then switch off when he's gone to England). You have to love and hate the colours, independently of this week's new faces.

Which is where the core strength of the league constantly threatens to be its biggest potential weakness, because those who are committed to the colours can be, more than in any other code, scary. Sydney FC has a solid core of support, but what held it back from automatic exponential growth in a city of four million was the perception of old NSL tribalism played out in a new shirt.