It's two different descriptions.
50% average is a rating comparison along a bell curve
70% average is a rating of the game's quality and proficiency.
The clearly retarded point being that if one year has a lot of top games, then the 50% scale actually reduces score, despite being a higher point average.
For example:
a scores 70 points
b scores 80
c scores 90
The 70% average says a passed, b did great, c did excellent
The 50% average says a underperformed, b passed, c did great
Now in another year
a scores 40 points
b scores 50 points
c scores 60 points
70% average says all did poorly.
The 50% average says a underperformed, b passed, c did great









