What the 5 placements actually decide after a soft reset
At the start of each Act, Val applies a soft reset: your visible rank is pulled down a few tiers, but your hidden MMR — the account's real skill estimate — carries over almost untouched. The five placement matches that follow don't rebuild that estimate from scratch; they resolve the gap between your lowered visible rank and the MMR you already held. That's why placements can jump you several divisions in a single run: the system is catching your badge back up to where the account was, weighted by how you play each of the five games. A booster's job here is to convert that hidden ceiling into the highest honest visible seed, not to invent rank you didn't have.