Make the system like RGC 5 psr per win - 3 per lose
Just like what valve does now, when after 10 wins in a row or something like that, it starts giving you +50 MMR.
We also track our uncertainty about your MMR. New accounts and those playing in Ranked Matchmaking for the first time have high uncertainty. Higher uncertainty allows larger adjustments after each match, and lower uncertainty leads to smaller adjustments. Together, the MMR and uncertainty can be interpreted as a probability distribution of performance in your next game; the MMR itself serves as the mean of this distribution and the uncertainty is its standard deviation. If the match outcomes (both the win/loss and individual performance) repeatedly match our expectations, the uncertainty tends to decrease until it reaches a floor. A surprising match outcome will tend to cause an increase in uncertainty.
Any form of metric is good for determining who is the best at that specific metric.Winning is the main objective of the game, therefore having winning as the metric is the best way to rank people.If other forms of rating were present, people would give up on trying to win when the game is even slightly difficult and they would instead try to farm rating points in those specific hypothetical ways.To give a small example, if you would gain some rating points for having x amount of last hits, people would afk on lanes to get those last hits instead of doing things on the map like they should.Another example, if you would gain some rating points for having y amount of kills, people would start using spells only to last hit the kill instead of using the spells when they should in order to win the fight.Yet another example, if you would gain some rating points for having z amount of k.d.a. ratio, everyone would start being scared of dying and not going in to do things in fights even if they should, (because every death reduces the k.d.a. ratio immensely), and so on and so forth.Therefore, having only winning as a metric is the best.