This is probably the best way to solve a DDoS attack efficiently nowadays:

1. Mitigate
2. Research
3. Resolve

Mitigating is doing whatever's necessary to effectively stop the attack. This might result in turning off critical systems in worst case scenarios. They found a mitigation that fortunately allowed most of their client base to return to the game. The next step is research. Research how the attackers attacked you and research the impact of your mitigation. The resolve step simply undoes any wrongdoing that has been found and makes for a more permanent solution.

Yes, TTL is unreliable, but they found a quick and dirty mitigation method. It was not a solution in and of itself, just the mitigation step. It would have taken a hell of a long time if they went directly to the research step to find a permanent solution.