It seems that not all are affected in the same way. For example I think if you are located close to one of the data centers where the EA servers are (I think in Europe it's Amsterdam) they are happy. Somehow even EA says that the servers are not connected in rivals (it's peer2peer) thats not true. I've bought a Netduma and seen that a "EA server" is somehow interfering.
So now imagine two guys from:
Amsterdam or UK are playing (both with great connection): all will be fine.
Hamburg and Amsterdam are playing (both with great connection): all should be fine, maybe the Amsterdam guy could have an advantage
Guy from Rome is playing against someone from Munich (both with great connection): at least for one the connection will be *, worst case for both. Due to the distance from Rome and Munich, but as well due to the distance to the EA servers.
To be honest: once look how slow the FIFA menu is from time to time (no idea how you can code a game that it's depending on a connection to a server), but in this case you can see how overloaded the servers and the network is. Aiaiai EA... I really hope you are resolving this once...
I've once played over 4G. The gampleay was laggy, but I did not have input delay. I was easily able to win, it wasn't fun, but I won. So it seems my opponent suffered from my poor connection...
BUT PLEASE: AT LEAST STOP PUNISHING THE ONCES WITH A GOOD CONNECTION!
