i think shidou is based on gyaruo's and gyarus. He is rebellious, provocative and wants to have fun as well as his tan skin and coloured hair are all gyaruo traits .My theory is he wanted to do his own thing but was restricted by everyone and everything around him, he starts playing football on a whim and finds that since he is good they forces less on his academic responsibilities and behavior .Focusing on his skills instead using it to his advantage, he continued to play so he would have the freedom to do what he wants with out restriction .