Home field advantage in the World Series means everything—at least, that’s what Major League Baseball (MLB) officials would like us to believe.

In an effort to make the annual MLB All-Star Game more meaningful and overcome negative fallout from 2002’s game (which ended in a 7-7 tie after 11 innnings), Commissioner Bud Selig decreed that, for this year and next, the league that wins the All-Star Game will get home field advantage in the World Series; that is, it will get to play games 1 and 2 and, if necessary, games 6 and 7 in its home stadium, giving it a presumed advantage. The American League’s 7-6 victory over the National League in this year’s All-Star Game, played July 15 in Chicago’s U.S. Cellular Field, means that whichever team wins the AL pennant will enjoy the fruits of that come-from-behind win.

In most other professional sports, the team with the better regular-season record is awarded home field advantage in the postseason. Since the advent of divisional play in 1969, baseball too has followed this practice during the league championship series. However, home field advantage in the World Series has continued to alternate each year between the National League representative and the American League representative.

The commissioner’s decision stirred considerable debate among baseball commentators, fans and players. Some critics of the new policy feel it is inappropriate to give one of the World Series teams an advantage based on the outcome of what is essentially an exhibition game. But before considering the appropriateness of using the All-Star Game to decide home field advantage, a question must be addressed: Is there really a home field advantage in the World Series? Does the team that plays the first and last two games of the seven-game series on its home field really have an advantage over its opponent?

The answer to this question is not obvious. After all, the team that opens the World Series at home only plays more games on its home field if the series goes the full seven games. In a four- or six-game series, the two teams play an equal number of games on their home field. In a five-game series, the road team actually ends up playing more home games than the team with "home field advantage."

A total of 76 World Series have been played under the current 2-3-2 home-away-home format that was adopted in 1924. (Because of travel restrictions during World War II, the 2-3-2 format was not used for the 1943 or 1945 Series, and no World Series was played in 1994.) Of the 445 games played in these series, the home team has won 254, or 57 percent. However, of these 76 series, 14 went only four games, 14 went five games and 17 went six games. Only 31 World Series went the full seven games. As a result, teams playing games 1 and 2 at home have played only 52 percent of all games on their home field.

Despite playing only slightly more than half of all World Series games on their home field, however, teams playing the first two games at home have won 44 of the 76 World Series, or 58 percent. So there does seem to be a significant advantage to starting the World Series at home. But why is this?

Among both critics and supporters of Selig’s decision, it generally has been assumed that home field advantage in the World Series is based on the fact that, if the series goes the full seven games, the team starting the series on its home field also gets to play Game 7 on its home field. Before the start of this year’s All-Star Game, Fox Sports commentator Kevin Kennedy claimed that the home team had won 15 of the last 17 World Series that went to a seventh game.

Kennedy was mistaken. In fact, playing game seven at home does not appear to be a significant advantage in the World Series. Contrary to Kennedy’s claim, home teams have actually won only 10 of the past 17 Series that went a seventh game. Moreover, since the 2-3-2 format was introduced in 1924, the home team has won only 16 of 31 seventh games (52 percent), far below the 57 percent success rate of the home team in all World Series games.

We have to look elsewhere in order to explain why teams that begin the World Series at home have won the Series 58 percent of the time.

It appears that the home field advantage in the World Series is due almost entirely to the momentum gained by playing the first two games of the series at home. Teams beginning the World Series at home have won Game 1 47 of 76 times (62 percent) and Game 2 44 of 76 times (58 percent). Even after losing Game 1, the home team has come back to win 17 of 29 times (59 percent) in Game 2.

Altogether, the home team has swept the first two games 27 times, split the first two games 37 times and been swept at home only 12 times. Not surprisingly, when the home team won the first two games, they went on to win the series 20 out of 27 times (76 percent). Also not surprisingly, when the home team lost the first two games, they went on to lose the series nine out of 12 times (75 percent).

Even when the home team split the first two games, they went on to win the World Series 21 out of 37 times (57 percent). However, when a split occurred, it made a difference which game the home team won. Home teams that won Game 1 but lost Game 2 went on to win only nine out of 20 Series (45 percent). In contrast, home teams that lost Game 1 but won Game 2 went on to win 12 out of 17 Series (71 percent). In fact, these teams were almost as successful as those that swept the first two games at home.

The conclusion that emerges from this analysis is that, in the World Series, momentum matters. Winning the first two games at home, or even losing Game 1 but winning Game 2, usually provides the home team with enough momentum to carry it to victory. Another telling statistic: Since the advent of the designated hitter in 1973, the home team has won nine of 11 Game 7s, but in the six Game 7s previous to that year, the home team won only once. This seems to indicate that, since the game is significantly different in the two leagues, that difference is amplified in the World Series and carries an even greater competitive advantage for the home team.

So there is a significant advantage to beginning the World Series on your home field, and if an American League team wins it all this year, it can thank the Texas Rangers’ Hank Blalock for his go-ahead home run against the Los Angeles Dodgers’ Eric Gagne in July’s Midsummer Classic.

But whether attaching so much importance to a heretofore "meaningless" exhibition game is an appropriate means of determining something so important is another question entirely.