I'm aware issues "out of their hands" can happen, but that's what fully redundant systems are for. In this case, all traffic seems to be dropping off somewhere in the Prolexic datacenter in Miami (a company that SPECIALIZES in DDOS mitigation). Why there's no redundant backup anywhere else in the country, I don't know - No matter how much trust DT puts in their provider, they need a backup solution to switch to (at another DDOS mitigation host) if something goes wrong with the first. What would happen if something like the "ThePlanet datacenter electrical closet explosion" incident happens?
If it's a DDOS issue, then the datacenter that was chosen is incompetent in their "specialty" - I don't care whether the issue actually lies on the network or sever end of a DDOS, hosts specializing in mitigating DDOS issues need to have both ends covered for their clients.