So, you're saying it was a lucky guess?
No, they were following a lead.
Right now they are talking about one lead that is interesting: someone turned in a bloody dodgers jersey to a dry cleaner 10 days after the opening night incident, saying to the dry cleaner that they were in a fight opening night, but “not the same fight.”. The dry cleaner was scared of this person and cleaned or began to clean the jersey, but then called the cops, who did confiscate the jersey. Whether there could be any dna left, or whether this promising lead led to this arrest is not known.