I started to collect the data because it seems that the ONE consensus in the community seems to be that nobody likes the 15-5 (or less) games.
So, here's the data:
It shows the strength of the correlation between very bad games being a thing, and the team being not balanced at all skill-wise. If someone wants to calculate the exact correlation coefficient, go ahead.
There are other factors, of course, like tank MM (yes, the 279e and the chieftain are very influential tanks), platoons, map balance, etc.
However, the number 1 culprit of very bad games seem to be WN8 discrepancy between the teams.
Some information on the data:
This data was extracted from post game battle results, so the anonymizer is irrelevant, the numbers are as true as can be.
This data concerns T8-9-10 games only, probably an average of T9.5 or so.
I didn't calculate the % of all games played that were very bad games, because I forgot to log some of those very bad games, especially toward the end of the list. But it's something like 8 to 14% of all the games played were very bad games. So… A bit less than what I was expecting, but those games occur mostly when you play early in the morning. At lower tier, those games are a LOT less rare.
I'll let you all draw your own conclusion about what needs to be done to makes those games rarer.