As far as I know, player with the best connection is going to be the host. And the rest of 'em will connect to him/her. And did each player have to maintain their connection with each other too? Because somehow when I played, if there's a new player joined in the middle of the match then it could ruin my connection.
Unlike previous CoDs, host is randomly selected at the beginning of each match.
In past CoDs, an initially formed lobby will select a host based on best connection. The host will keep host until he leaves, and then the lobby will either disband or select a new host. Which meant when a good party formed, it would keep host all night.