Communication is overrated, I think I win about 95% of the games I play with kurt, but we never talk tactics.
It's probably more like whilst your team is all on A at the beginning, they have 2 or 3 going for B, and a team of good players will keep killing you off. Plus it's also so much easier to cap a flag when there is two of you on it. The extra 4 or whatever seconds it takes are where you tend to die by yourself.
At least with people I've played nobody ever takes tactics or anything like that seriously.
The best thing to do is backout whenever you see a full party or when the teams look unbalanced, I do it all the time. It's not as if you get punished for leaving a lobby, just leave it and find a new game.
I'd love to just back out of a lobby but if I did that then I'd never get a game at all, what with all the connection issues. I can't wait for 30 minutes to find a game that doesn't crash only to then quit ! I'm taking whatever I can get at the moment which seems to be lopsided lobbies.
When I say tactics , I'm not talking over-elaborate strategies, just more along the lines of " I'm going for B, cover me etc".