Rank means absolutly nothing, and has no relation to being promoted.
The only way you'll be promoted is by consistently beating people in other leagues above you, and you won't be promoted till your win rate against those above you balances out to 50%ish, so that blizzard doesn't have to promote you twice.
So, if you're playing people in leagues above you, and still winning a lot, just wait till it balances to 50% wins and you should be promoted. If you're still facing bronze leaguers you won't be promoted.
My win ration is about 75% atm, last night we were going keen and pretty much destroying people, all the others were getting promoted and i'm just sat stuck in bronze

Ah well gives me an excuse to keen tonight




