Well, i think we need a clear tactical team, so this is my idea:
1 player full offense, walks whole map, trying to get the flag, trying to counterattack when enemy is near our flag.
1 player full defense, walks till half of the map, not trying to get the flag, defends own flag and flagholder, not using nades only firepower
1 player off/def, helping to get the flag, throwing nades, help escorting flagholder to save part of the map, defending flagholder and also keeps the enemy busy with nades or firepower, counterattack together with off.player.