OkapiWoods:
I am a casual player for about 2 years, mostly playing the Coin Rooms. Nevertheless I got promoted to Master with an average of around 68. Then it went to 78 a few days ago, when the avatars were retooled./
Is there a new way of averaging scores or did they just correct it?
Your first Ranked Round as a Master was a 39 in a Nine Hole Bracket Tournament. Double the 9 hole score to make an 18 score for your average and voila, 39 x 2 = 78.
Now that you Tiered up your average will be based on an average of all Ranked Rounds played at Master Tier until you have accumulated 40. At that point you'll "saturate" and your average will be based off the lowest 40 played at Master Tier (your average will never go up again until you Tier up again).
If you play almost strictly coin rooms it's possible you'll Tier up before reaching 40 ranked rounds as a Master because coin rooms have their own algorithm, but unfortunately no one really knows exactly what that is.