The mechanics and ways of the Community Warfare are actually that erratic I can't say much about it. I only had like 3 games, but those were quite enlightening concerning Invasion Mode gameplay.
The first game was IS defender vs Clan attacker on the snow map with 2 entrances. The attackers were basically butchered at the gates. Was quite boring for the defending team.
The second game was IS attacker vs Clan defender. Attackers got totally butchered. Feels so ironic when you rush the landing point hunting for attackers.
Third game was remarkable. Clan attackers vs IS defenders. It was the swamp map, and the defending position sucks. IS defenders had lined up as usual behind the gates. Clan attackers all broke through one of the outer gates and rushed past the IS mechs, ignoring them totally. As a defender I was shooting like mad, hitting rear armor all the time, but those Direwhales blew up the cannon in no-time, simply having confidence that their armor lasts longer than it takes them to blow up the cannon. Amazing.