We apologize if you have experienced issues with our matchmaking system.
We learn from our users and our players every day, and we are continuously improving our tools to match up players with others more similar to their level and allow for fairer, more balanced battles.
Being matched against players from very different rankings than your own should only be happening if you are experiencing long queues (more than 5 minutes) and it is intended. If you want more balanced games and continue waiting in the queue, please activate "strict matchmaking".
You can find it in League > Settings > Matchmaking.