They would go by guesswork and rumors. If you're used to the streets and know the city well, you'd know who had the orb, or were rumored to have the orb, and where the goal was. One would also know who to watch out for more than others. An inexperienced player or streetkid without the propper gear who enters the game would be an easy target for people who had participated for a long time and were/are streetsmart.