once you've passed the 30 games, it becomes difficult to understand your score, because you have to subtract from the points that you earn (new matches) those that you lose (match that you have already played but not counting more because they are beyond the 30 games).
if you position in second place but the 31th games is a first place, your average drops even if you're under 16 points average , because actually your placement points drop by 8.
for that reason i've asked to highlight the last 30 games.
sorry but my english is very poor