Provisionals are confusing sometimes

so i'm playing through them, i win a few, and suddenly the game is like, way slower pace, 4/10 people have a ping over 300, people are just walking into people and dying, so i think holy shit am i bronze, but i check, it's the same gold 5 ish area i should be at winning my first 4-5 games

why are the games night and day different in the same mmr range? like you could be in a silver 1 game of people who are decent at the game and working towards gold, or you could be in a gold 4/5 game where you are legitimately curious how they ever got out of bronze 5, the ranking system seems to have little legitimacy lately...