3v3 Provisional are messy

Me and my friends just started doing ranked 3s and finished our provisionals right away. We won 3/5 matches and we were kinda surprised to find out we got bronze 4 as our league/rank. The more surprising thing we found out is most of the matches we had didn't have bronze, only about 2 games and there were two bronzes in that but in the rest of the matches, it was silver only and above, we even got matches up with golds and a diamond but ended up being here. Any explanation why we ended up here?