I think that the value of rituals and superstitions is basically the boost of confidence and the sense of control that they provide an athlete. If an athlete believes that doing a specific action or behavior will make them perform better, then they probably will perform better. For instance, if a hockey player thinks that playing with his favorite stick will make the team win, then he is more likely to perform better. This is not because he has the stick but because he mentally thinks that and therefore he will perform better and play a good game.
I personally do not remember having any superstitious beliefs or doing any kind of rituals before soccer games. Although I remember when I was a freshmen in high school, I use to have a lucky pencil that made me do great on my tests and exams. So I would always write with that to get good grades. I was aware that it was just a superstitious belief but I still did it anyway because I was getting good grades.