Do League of Legends Ranked Fives teams face series for promotion?
I am on several ranked fives teams and don't recall having to complete any series. Not sure if it is because our MMR is high or because series are non-existent in ranked teams.
Just like in solo you have to win a series to rank up. You probably have not reached that point with a team yet, or just did not notice. Remember that you have to reach quite a lot of points before entering a series.