Baseball has never really had much of a home-field advantage, especially when compared to the other major professional sports. In football, a loud endzone crowd can influence an opposing team's offense and cause false start penalties. In basketball, fans can have their collective voices reverberate off ceilings and cause distress to foul shooters. Even in hockey, fans can sneak into the control booth and turn off the freezers, thus melting the ice and causing general havoc.
But what of humble baseball? Historically, home teams usually win about 51% of games, barely an advantage at all. This season, however, everything's been turned on its ear: home teams are winning a whopping 57.5% of the games. According to Baseball Prospectus' John Perrotto (subscription req'd), that's the highest home team winning percentage since 1931, when it was 58.2%.
The Red Sox lead the way with 26 home wins out of 33 games. That's almost a 79% success rate! Oakland's winning record is based mostly on the fact that they've played ten fewer games on the road than at home, where they are 21-16. The pitching staff has only given up 24 ding-dongs in 345 innings in the cavernous McAfee Coliseum. That's a real home-field advantage, especially for a team whose strength is not a reliance on tater tots.
Perhaps Oakland's location in the Pacific time zone helps too. According to the good people at Scientific American magazine, jet lag causes a slight disadvantage to visiting teams:
"So, let's say the New York Mets have to travel cross-country--and, so, through three time zones--for a four-game series against the Giants in San Francisco. According to the new research, the Mets would have a three-hour disadvantage, or 60 percent chance of losing the first game; their odds of winning would rise from 40 to 48 percent by the second day, and the Giant's advantage--at least the one based on circadian clocks--would dwindle to 51 percent by the third day. If there was a fourth game in the series, the teams would be equal in terms of their body clocks."
Flying across three time zones screws up one's Circadian rhythms, causing sleep deprivation and slows down players' cognitive and motor-skill abilities. Basically, if you don't get a good night's sleep, you won't be able to react to a 95 MPH heater from Tim Lincecum. Actually, most of the weak Mets team wouldn't be able to react to a 95 MPH heater from Tim Lincecum in Shea Stadium either.