Just how important is home-field advantage in Major League Baseball?

With the St. Louis Cardinals and Oakland Athletics hosting the Pittsburgh Pirates and Detroit Tigers, respectively, in two winner-take-all games in the American and National League Division Series, fans of the two former clubs might want to know just how much of an advantage home field really is.

To find out, we perused the results of every postseason over the past 10 years in MLB, as well as in the three other major American professional sports—for comparison's sake—and marked down each time a team in the host position won the series or game. The outcomes were then totaled to come up with a percentage that reveals all.

Let's have a gander, shall we?

Major League Baseball 

(*Note: Adding the extra wild card—and the wild-card play-in game—last October, pushed the number of playoff rounds from seven to nine.) 

The baseball playoffs are the most challenging to make among the four major pro sports, simply because the fewest number of teams get in—only 10 in total. Hence, there were 70 postseason series and two wild-card games from 2003 through 2012.

Amazingly, the team with home-field advantage won only 37 of those matchups, which translates to 51 percent overall. Basically, home field holds no advantage in baseball.

Part of the reason for this, to be sure, is that there are now one-game "series" as well as two five-game sets where other sports have seven-gamers. Let's keep that small sample size argument in mind as we move onto football, where the postseason is made up entirely of one-game matchups.

This table simply lays out the number of times in each MLB postseason the team with home-field advantage won its matchup. The most instances in which a club with home-field advantage won in each October is six (out of seven series) in 2009, but in 2006 only one home team won at all—that's rather remarkable.

Even more noteworthy? In four of the past 10 postseasons—2012, 2010, 2006 and 2003—the teams who didn't have home-field advantage won more series than the clubs who did.

National Football League 

Football's postseason consists of 12 teams in total, more than baseball but fewer than basketball and hockey (which we'll get to in a minute). As a result, there are 10 playoff games each year, not counting the Super Bowl, which is played at a neutral site (and wasn't included for the purposes of this piece).

As you can see by the table, the home team won 59 times in those 100 matchups, which makes the math easy—the home team won 59 percent of the time. That's a more noticeable home-field advantage than in MLB. But just wait until the next sport.

Again, this table displays the instances in which the home team came out on top in each NFL playoff season. The range is from eight in 2011 and 2006 down to four in 2010 and 2005.

Unlike in MLB, however, those latter two seasons mark the only times that road teams won more series than the home teams.

National Basketball Association 

Basketball's playoffs are made up of 16 teams overall—that's more than half the league, by the way—which is more than both MLB and the NFL. That means there are a whopping 15 series every season for a total of 150 over the past 10.

Here's an impressive stat: 109 of those matchups were won by the club with home-court advantage—or 73 percent. Now that, folks, is an actual advantage. 

In this table, you should notice that the range is much smaller, spanning from a high of 13 series wins for teams with home-court advantage in 2008 to a "low" of 10 in four different seasons. Put another way: In no NBA postseason over the past 10 years has there been less than 67 percent of teams with home-court advantage winning their respective matchups.

In the NBA, home court is a true advantage.

National Hockey League

(*Note: There was no NHL season in 2004-05 due to the lockout.)

Similar to the NBA, hockey's postseason includes 16 of the 30 teams, making for 15 playoff series each season.

Of those 135 series, teams with home-ice advantage in the NHL came out on top 80 times, which is 59 percent. By comparison, that's the same as in the NFL. Home ice is, in fact, a clear advantage. 

The range for hockey's playoff series won by home teams goes from a high of 11 in 2004 to a low of six in 2012. That's a fairly wide range, but realize that the low happened only once and that it was also the only instance of a postseason in which more clubs who didn't have home-ice advantage won than those who did.

Bottom Line Comparison

To spell it out in one spot, here are the percentages of postseason matchups won by home teams in each of the four major sports over the past 10 seasons, listed in order of most to least:

• NBA: 73 percent
• NHL: 59 percent
• NFL: 59 percent
• MLB: 51 percent

The conclusion, then, should be pretty clear: Home advantage is definitely tangible in the NBA and a pretty clear in both the NFL and NHL, but in MLB, it's pretty much a non-factor. In many ways, that's rather appropriate given how much of a crapshoot the baseball playoffs are considered.

Applying these findings to the 2013 baseball playoffs—at least so far—proves much the same. Of the matchups that have been decided to this point, the clubs with the so-called home-field "advantage" in the postseason have been the Cleveland Indians and Pittsburgh Pirates in the wild-card games, and the Boston Red Sox and Atlanta Braves in the Division Series round. While the Pirates and Red Sox took care of business, the Indians and Braves lost.

That means that the current rate of success belonging to the home teams is—you guessed it—50 percent.

Depending on what happens Wednesday and Thursday, if either the Athletics or Cardinals wind up falling short while actually playing on their home fields in Game 5 against the Tigers and Pirates, respectively, it will be further proof that baseball's postseason is as whimsical and hard to figure—and dramatic—as ever.