This is not to say that the home team will win, but they do have an intangible but quantifiable benefit from playing in a friendly environment, before their own crowd. It is as psychological as it is real. The players are just that much more comfortable by virtue of the familiarity of their surroundings. This translates to most aspects of life, not just sports. Machiavellian business executives speak about the psychological advantage of conducting negotiations on home turf.
Restaurants breed customer loyalty through familiarity.
Children grow uneasy when their parents leave them at home with a baby-sitter. We all remember the chaos that reigned when we had substitute teachers in school. Nope, it was because their presence broke the familiar pattern to which we were accustomed. Warren Buffett and Peter Lynch have always espoused, especially for individual investors, that we buy what we know. The rules under which Lynch had to operate when he managed the Fidelity Magellan Fund made this simple rule not practical for the amount of funds he had under management.