Conversely, why do you feel much better about things in general when your team is dominating and others are going through the down cycle?

In both scenarios, you have absolutely no material impact on the outcome of the way the ball bounces, the way the other team prepares, who gets injured, or whether the team will match up, dominate or get dominated. Why do you let it affect your happiness either way?

Sports are one of the desserts in life. They are not your healthy balanced meal. You enjoy desserts after you have been nourished by the essentials. If all you eat is dessert, then you'll have some bad life outcomes, not limited to moodiness and depression.

Sometimes dessert is no good, so I don't eat all of it. But most of the time I like it, and sometimes it's awesome, and I LOVE it. Either way, it's over quickly even if it's fun to talk about on facebook.