If you're on a server with 3 players with the same clan tag most likely they're in a squad and are going to be on the same team next match. If this is screwing up the balance, you can just leave (not saying this isn't a problem- see new solution idea below).
But the harder problem is guys that squad that don't share a CT (do it myself all the time). When this happens it can take a few matches of getting stomped before you figure it out (if ever). So the obvious simple solution is to highlight players names that are squaded on the leaderboard, just so you know that there is no hope next time.
On matchmaking balance..
It's obvious they use rank to split up teams. So all they would have to do is put a total level limit on squads.
Here's an example:
Limit 100- so total rank of players in a squad cannot exceed 100.
So squad can be 2 X 50's, 3 X 30's, 1 X 50 and 2 X 25's, sure you get the idea.
What do you guys think?