What your placement matches actually decide
Placement boosting is about the ten placement matches that set your rank rather than any climb afterwards. On a fresh account those ten games calibrate your starting rank from scratch; at a season reset they re-seed a rank you already have. Rocket League runs a soft reset between seasons — your MMR is pulled toward the middle, so you finish placements a little below where you ended last season and re-climb from there. That soft compression means a strong placement run matters: it decides how high the system is willing to seed you before the grind even begins, and unlike a full rank boost, placements are outcome-sensitive matches, not a promised tier. We play them at peak win rate to seed you as high as the reset allows, but the exact rank depends on how the ten games resolve.