I wonder whats the reason for that. Maybe asicminer is too poorly connected to other wallets? I mean a miner that is connected to as many wallets as possible and those wallets are again connected to as many miners as possible should have an advantage against a miner that is poorly connected because the block that is accepted by most miners wins. When i understand it correctly. So i only see that as an explaination. I doubt a internet connection can be that bad to have such a big effect.

We've seen AM's "data center", so who knows what ISPs were chosen. Running services out of mainland china is not as simple as you'd think:

https://bitcointalk.org/index.php?topic=99497.msg2733783#msg2733783