Like he said above, the soft reset at end of season 2 puts you in a elo point depending how you did on the end of season 2. I was around 1400's end of season 2 and started season 3 with 1325. So naturally higher elo players would start season 3 at a higher elo. There's also double elo on your first couple of games. Not 100% sure on exactly how it works but you do gain/lose more elo during your first 50 games in order to get to your elo "skill level" quicker. This decays slowly the more games you play. So a player losing their first 5 games and winning the next 10 would gain less elo than a player winning their first 10 games and losing the next 5.