The admins managed to stop the other DDoSer some months ago, cause it was easier. He made a topic and the admins took enough information about him from that. That case was easier in my opinion.Just like the admins managed to stop the other guy who was DDoS'ing the servers some months ago, I think they could have done something similar again. They could even report it to some cyber crime agency.
But this case is different. We don't know anything about the DDoSer.The only thing that we would know is his IP. But, do we know it? Anyway. On the other hand, as you recommended, a report to a cyber crime agency would be a good move.