Not sure how other games handle this, but CS and Black Ops 2 made it so if you put a group of 5 people together that’d be a team, but if you switched one of those 5 out, then that’d be considered a different team. I didn’t really like that as I just thought that it convoluted the rankings and made them inaccurate. I’d like to see teams akin to clans.
Possibly two versions of a ladder where in one you can be on as many teams as you want (no player or team limit) and on the other you can only be on one team and the team must field so many players.
I wrote an extensive article here regarding match making and ladders: http://dirtybombers.com/gaming/servers-matches-and-ladders-oh-my/
But, beyond that there were some really good suggestions and ideas in the comments/forums from people who aren’t even in the alpha.