Leaderboards seem a little shakey
In theory, if u played against way worst ranked players than u, u could lose a lot of rank just by losing one game.
But a good matchmaking system will avoid this extreme matches and make u play against somewhat close teams.
Either because the matchmaking system has some bug or there isn’t enough playerbase to make the matchmaking system work fine, it seems to be some problem with it. If the matchmaking was working well, almost everybody should have a W/L ratio close to 50%, and that’s far from reality.