Unfortunately there are some players who believe that they should always beat a lesser player, and this is just not true. If I know I am a better player than my opponent, this only means that I should beat him more often than not. It does not mean that I will win a particular game, or match. Your SL9 opponent may not understand this, which means he is going to experience these periodic bouts of frustration, and he'd better learn to deal with them. If I get beaten by a SL6 I just shake hands and move on. I'm not going to win every time, even against the worst of opponents.