I’ve been playing a while… and from what I have gathered:
It doesn’t matter whether it is a win, loss, draw or vote surrender:
A loss always gives me about -27% to my ranked progression.
A draw always gives me about -3% to my ranked progression.
A win always gives me about +17% ranked progression.
In order to actually go up a rank I need 7 wins for every 4 losses. A 1.75 win ratio, which is a rather tall order. It is fine in the bronze ranks where it is easy to win all on your own. However, since you cannot escape having those bronze ranked players in the higher silver ranks - you just cannot win enough due to matchmaking issues.
Thus what I would suggest is that you actually put the win and loss bonuses to the same line. Good players would not be stuck at that silver rank bottleneck, they would advance higher to the ranks. Thus lower skill level players would not be pitted against players that they have no chance to beat, and with higher number of higher ranked players it would not take so long to find a match.