With their victory on Sunday, the Astros locked up the NL Central title and the top seed in the NL playoffs. The top seed in the Senior Circuit gets home-field advantage all the way through the postseason, as the NL has the extra home game in the World Series this year.

In the long run, however, how important is home-field advantage in the baseball playoffs?

Recent history suggests it's not. For example, in 2000, the team with home-field advantage won three of the seven postseason series. Home teams were 16-15 overall. In 1999, they did much better, winning four of seven series, with a much better 20-11 overall record.

Let's break this down for each year of the three-division era:

(Note: throughout this article, the strike-induced Division Series of 1981 are disregarded.)

Year	Series	Record
2000	3-4	16-15
1999	4-3	20-11
1998	4-3	14-16
1997	2-5	17-17
1996	4-3	14-18
1995	3-4	19-12
Overall	20-22	100-89

There's not much gain to being a home team, even after you consider that in the last few years, home-field is determined by regular-season record, meaning that in theory, HFA is going to the established better team. (The wild-card team can't have HFA, which screws this up it some years, as it did in 2000 in the AL and will again in 2001 in both the AL and NL, so take that with a grain of salt.)

Is the seeming unimportance of home-field advantage a recent phenomenon? No:

Decade	Series Record
1990-93	8-4
1980-89	16-14
1970-79	15-15
1960-69	3-9
1950-59	3-7
1940-49	7-3
1930-39	7-3
1920-29	6-4

Up through World War II, home-field advantage seems to have been significant. What's weird about this is that several World Series in this era were played entirely in one park, so it's hard to draw conclusions. Since then, though, there appears to be no advantage to having HFA in the postseason.

Some of you are probably thinking, "OK, there's no overall advantage, but what about when the extra game makes a difference?"

In series that go the distance, when the home-field advantage should have its greatest impact, the home team is 29-24 since 1920. It's worth noting that there's been a significant shift in favor of home teams in deciding games: since divisional play began in 1969, home teams are 20-12 in deciding games.

Given all the factors that go into winning a single baseball game, especially one as important as the deciding game of a series, concluding that playing at home is the determining factor is a big leap, and one not supported by the data. Yes, we can point to anecdotal evidence -- the 1987 and 1991 Twins are popular that way -- but on the whole, home-field advantage appears to be small potatoes.

So as discussion of the home-field advantage comes into the fore, remember that it doesn't mean all that much. Yes, there are benefits, the potential for less travel being foremost among them. The day or two of rest for the regulars, and setting up the rotation for the playoffs, are more important.

The team of writers from the Baseball Prospectus (tm) writes twice a week for ESPN.com during the baseball season. You can check out more of their work at their web site at baseballprospectus.com. Joe Sheehan can be reached at jsheehan@baseballprospectus.com.