The quit prevention system is silly - it would be fantastic if it worked correctly, but IMO it doesn't right now. I can play game after game on FIFA 12 fine, lag free. But on PES, two games in a row I've been forcibly disconnected by the game, with no warning or anything I could do to stop it, because "network stability has significantly worsened" - on the second game, there wasn't even any visible lag, so I don't know why I was disconnected.
This wouldn't be so bad, but you then get a message that you need a 70% match completion rate over 10 games or you'll have various restrictions applied online. This again would be fine, but apparently these forced disconnects count as me quitting a game, despite the fact I couldn't do anything to prevent the game booting me to the menu.
So now, I have to hope that 7 of my next 8 games manage to avoid these silly forced disconnects, or it's hello restricted online features. Since the game has logic that decides when the network is too unstable, and kicks users, then why couldn't they implement a check that says "if forcibly disconnected by the game due to network, don't alter DNF percentage. If disconnected any other way, alter DNF percentage." That would have made more sense.