As I understand it, the squish is needed because of their fat-in-the-middle divisions.
If there is 10% in div 1, and 25% in div 2, then there are more than twice as many players that got a win in a round in div 2 than got a loss in div 1. So more players get a SR increase than lose it. Near the division boundary, that means more players move up than down.
The same goes for your 30% div 3 compared to 25% div 2. More players in div 3 gained SR than div 2 players lost SR.
The same thing happens in the other direction too. Divs 1 and 5 grow by quite a bit over the 3 rounds, divs 2 and 4 grow a bit, div 3 shrinks.
The squish is supposed to counter this, pushing all players back towards div 3.
The other thing that could happen is one or a group of players win a bunch and gets out of reach of others at the top of k1. I guess the squish is to counter that too.
I have no idea why aurodium all get squished down.
Wouldn't the need for squish (apart from runaway players) just go away if they set the divisions at 20% each? Same amount of players move up and down each round, regardless of division. 20% each would be self-regulating, just leaving something to be done about runaways.
