It is working, but I wouldnt just rely on it and do noghint because it only balances out the playernumbers. If it would balance out so that teams SR or some rating would be equal - I would trust this more. Nowadays, we just throw around the last person who joined.
Mini, i love your reasoning and fully agree. Hope to live long enough to see a day when its not a rare coincidence but a trend.
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I know we all would love nice and working automatic solutions, but since this system still has its learning curve (some people dont have SR value, some have way too high or low to their actual skill level etc) we should be a good host and try to make playing enjoyable to our guests and ourselves also. Nothing wrong with also swapping with someone etc.