For your information: I'm about to finish on day 8 with the American resistance. We entered the game with 4 Regulators: Mod Torpedo, SMod Eminem, ex Mod Crazy Pigeon eyes and me. The four of us might be a bit more skilled then the average player and we work well as a team but it is the proof that a team of 10 players that communicate in their chat and work together can win this map.
From what is posted here, it seems that the norm is to have a maximum of 2 active players per team. Having 4 skilled and active players that work as a team from Day 1 is immeasurably advantageous. So much, that one could even claim that it is unfair to non-alliance players who entered the map in order to play with random partners.
If alliances are to enter as a group in the game, it might be better to show (for example, in the Join screen) that the team map you are about to enter will see you facing a "block" of some alliance. Then you can decide to enter only if you can guarantee that you have members of your alliance in the team, or other players with whom you have agreed to play together.
I agree that this (as also the other team maps) are better to be played by alliances. If so, then perhaps some advance notification would be helpful.