From my experience it works terrible.
Some examples:
3 silver, 2 gold VS 3 cobalt, 2 gold - I was on the unlucky side and lost in 4 min (defender side), was aunable to play ebcause silvers had like 2/20 stats
11 games win streak (but I can be wrong) and I am still in same division (Gold 2), while me and my team is aspiring for cobalt, not getting any rank ups after so amny wins (stomps).
And now I am playing 1 vs 5 game, we met again gold 3/2 players in enemy team we played previously, they decided to leave instead of play against us.
Games where I have 3 unranked guys on lv 6 that has no idea where to go and enemy has everage level 25.