@MariusRZR696 there might be some truth in what you are saying about the sheriff - maybe SBMM takes into account the most recent events and stats. E.g. you win a game or have a high kill game, next one will be a tougher lobby for you as game things you are too good for the previous day lobby now. At the same time pro players (assuming you talk about them) get smacked in public lobbies (I think that does happen, they are not godlike after all) - so at that point your stats might be comparable and yours might be even better.
I am quite sure game is not taking into account you "whole" stats over multiple splits and seasons etc. otherwise that would level out over eternity and would keep placing much better players in weaker lobbies as their progress would be way ahead of "average" stats.