I may be able to help add some insight to your question, although like bard and them said its best not to worry about your league and just play

I was curious about the same thing as at one point i was getting seriously annoyed that as a bronze I was facing master and diamond league players.
So I IM'd Blizzard on it. Basically what the ytold me is the rank of the opponents you face are based of your last win/loss - Meaning if the previous 2v2 game you played you won and got say 25 points
you are most likely going to be facing higher league players in your next match, but if you lost your previous match w/ the same points lost, then you will most likely be playing lower league players.
Its sounds weird I know, but that is the info that I got when I asked about it.
in short it only takes one good win with good points to be pitted against higher league players.
hope this helps
