Personal ratings are similar to team ratings. When you join a team, your personal rating is set to 1500, as you win or lose, you gain or lose points just like team ratings. Where it's different is say you play 7 games and win 7 and your rating is 1700(personal and team), then your partner does 3 games with your other teammate and they lose all 3 games, your PERSONAL rating would still be 1700, because you didn't lose the games, therefore your personal rating remains the same even though your team rating went down.