Placements Explained
Based on all the issues lately, let me explain placements.
Last season you were X, this season after placements, no matter how you do because they don't matter really, you'll more or less be X +/- Y, where Y is at a few sections.
For example, you were Silver II last season, went 10-0 in ranked, you'll be at best Gold I and at worst Silver IV.
Another example, you were Silver II last season, went 0-10 in ranked, you'll be at best Silver II, at worst Silver IV.
Remember, in the end, all that matters is MMR. Riot only does a soft reset.