Part of the explanation, Jamieson says, may be that playing in front of an unfriendly crowd can cause subtle but possibly significant degradation of the complex skills that athletes have developed through extensive practice. It's not the distractions, necessarily, but the crowd's jeering when a player makes a mistake.
The negative feedback, he says, can raise a player's stress level, and cause a player to try to compensate by concentrating on specific parts of his baseball swing or his basketball jump shot. When players do that rather than simply performing the entire skill as practiced, it's a recipe for disaster, he says.
"When you do performance monitoring -- that is, trying to do something carefully so that you don't do it poorly -- you're basically trying not to lose. Instead of thinking about winning, you're trying to avoid being booed."
There's also evidence that officials are influenced psychologically by the home crowd's emotional response to plays.
A 2007 study by Harvard University researcher Ryan Boyko, which looked at 5,000 English Premier League soccer matches involving 50 different referees, found that away teams tended to score fewer goals and give away more penalties, which suggests that officials made calls in home teams' favor.