Psyonix have written a post revealing how Ranked Season Play will work going forward, how it differs from standard matchmaking and what changes will be made to the system to make it better.
For traditional matchmaking, the game tracked your wins and losses, assigning a skill level (MMR) based on that. The system also factored in an 'uncertainty' stat for players that don't have many games recorded - over time this stat would go down as the system became more confident it was judging your play correctly.
To determine your division in a season more efficiently, there will be a 'points' (RP) system layered over the top. Now you gain or lose RP in proportion to the difficulty of the matches you play. This difficulty is based on each player's MMR, not RP. Your RP will only come into play when assigning you to a division, with matchmaking still limited to going off your MMR stat.
Additionally, placement matches should be on their way, with Psyonix aiming to bring them along for Season 2. These tweaks will no doubt see the eSports world begin to look at Rocket League even more closely as it refines and becomes a fairer, more level playing field.
If you'd like to have a read of the full details, the official post can be found here.