[Mel_Ott]

Let's not forget the advantages to the home team of sleeping in your own bed (as opposed to some hotel room); having family and friends nearby; having a regular 'routine' ; having the support of thousands of fans in the seats; (sometimes) not having to travel; etc.

As an example, there's a condo development across the street from Pac Bell Park. A number of Giants have condos there precisely because they can roll out of bed, walk across the street, and be at the park. Compare this with having even a moderately long trip from a hotel to the stadium - the team's going to be more relaxed, more comfortable, and less tired.

Individually, each of these effects is probably quite small; but taken together, they make a difference - a difference that appears to be reflected in stats and standings across North America's 'major' sports.