I tend to side with Ghostdancer in thinking that the problem is the new netcode.
HTC have said they've changed the netcode in several ways to favour things like nearby enemies. I've seen the SEA full before and I doubt they've actually dialled back the bandwidth, yet nothing like this has ever happened before.
My ping times tripled or quadrupled during the problems. When I went and checked the SEA later in the event (40 ppl left) ping times were back to normal.
Heres my 'guess':
The beginning of each ToD has always been riddled with warps, as squads launch, the text channels fill, and the voice channels fill too. After a few minutes this calms down and the ToD goes on normally. Because its the beginning of the frame and no one has engaged yet the warps only screw up formations initially.
So we all roll... whammo, 200 plays suddenly get 'warpy'.
Next, the new netcode steps up, sees the 'warps' and decides everyone is lagging. It decides to switch all 200 players over to TCP mode from UDP mode.
200 players switching from TCP to UDP mode screws over the server something chronic. Some of us log, and eventually relog in. Those that stayed end up with TCP connections that are ok, but slightly laggy/warpy.
It was interesting to note that voice comms stayed ok during the whole fiasco, albeit a little choppy. Which would tend to indicate the bandwidth was ok.