Homefield advantage more important for some teams (Reds) than others (Rangers)
Outside of the American League wild-card race, the only relevant parts of the postseason picture left to be determined in the final weekend of the 2013 Major League Baseball season are homefield advantage (the Cardinals have clinched at least a tie in the NL Central). On that front, however, things are still wide open. None of the six division winners have yet been eliminated from the race for homefield advantage throughout the playoffs, and just one game separates the top two teams in both wild-card races. In the NL, the Pirates and Reds will play three games this weekend in Cincinnati to determine if Tuesday's Wild Card Game will be played there or in Pittsburgh.
So how important is homefield advantage in the playoffs anyway? Three years ago I attempted to answer that question and found that, from 1998 to 2009, the first 12 years in which the 2-2-1 homefield arrangement was used in the Division Series, teams with homefield advantage were 45-39 (.536) in postseason series and 37-35 (.514) in the first two rounds, the only two in which homefield is determined by regular season record. Given that the team with the better record (and thus, theoretically, the better team) is the one with homefield advantage in those rounds, being just two series over .500 suggests that homefield is meaningless.
That said, the importance of homefield advantage most likely varies from team to team and series to series.
For example, this weekend's battle to determine who will host the NL Wild Card Game involves a Reds team that has gone 49-28 (.636) at Great American Ballpark this year but is just 41-41 (.500) everywhere else. Only the Indians and Braves have a larger home/road split among the 11 teams still battling for playoff position. So while playing at home may be less important to the Pirates (.617 at PNC Park, .526 away), it would still be to their advantage to force the Reds to play in Pittsburgh on Tuesday. Ironically, the fact that these final three games are in Cincinnati increases the chances of Tuesday's game being there as well.
The most significant battle for homefield advantage, however, is in the American League wild-card race, as the Rays, like the Reds, are just .500 on the road and the Indians are one of just two playoff teams (the Braves being the other) to have a losing record on the road. In fact, the Tribe's .487 mark is the worst road winning percentage of any of the surviving teams. Tampa Bay holds a slim one-game lead on Cleveland heading into the final weekend, which finds both teams playing on the road, the Rays in Toronto and the Indians in Minnesota. Of course, the Rangers remain very much alive in that race, just one game behind the Indians while hosting the surging Angels, but homefield advantage isn't a concern to them. Of the 11 teams still alive, Texas is the only one with a better record on the road (.556) than at home (.551).
Getting back to the Braves, they are tied with the Cardinals for the best record in the National League, but would have homefield advantage in a potential matchup with St. Louis by virtue of winning the season series between the two teams. Atlanta's 40-41 road mark, however, means this weekend's home set against the Phillies is important to the Braves even though they clinched the NL East last Sunday. The Cardinals are hosting the last-place Cubs this weekend, which will make it tough for Atlanta to stay ahead of St. Louis and maintain homefield advantage in a potential Championship Series matchup. The Dodgers are three games behind both teams with three to play, but they also have the smallest discrepancy between their home (.590) and road (.556) records of the 10 teams currently occupying playoff spots.
In the American League, the Tigers are three games behind the Red Sox with three to play, but just one game behind the A's. All three teams have similar home/road splits, with the difference between their home and road winning percentages being between 91 points (Tigers) and 104 (A's), on par with the Pirates' split. That's above the major league average (a 77-point split), but below the average split among the 10 teams currently in playoff positions (115 points).
The biggest advantage conferred to home teams in baseball, of course, is last licks. It doesn't seem like a fluke that the last seven World Series to go to seven games were won by the home team, five of them featuring a walk-off win in either Game 6 (1985, '86, '91 and 2011) or 7 (1991 and '97). That would seem to make homefield all the more important for the one-and-done Wild Card Game. Of course last year, in the first year of the Wild Card Game, the road team won in both leagues, and if you fold those results in with the nine one-game tie-breakers in baseball history, the road team has gone 6-5 in those one-and-done games (though two of those home wins were walkoffs: the Rockies in '07 and the Twins in '09).