November 6th, 2013

Home Field Advantage in the World Series

Boston Red Sox logo_aThis short piece appeared in the 2013 World Series program in edited form, as a sidebar to a longer essay by Stan McNeal titled “Feeling Right at Home.” With the Red Sox clinching at home for the first time since 1918, the trend toward home-field clinchers would appear to be confirmed for all time … maybe.

Clinching a World Championship at home is more exciting for victorious players and their fans. And since 1980, there has been much cause for celebration, as teams with home-field advantage have won 25 of the 32 World Series played [including 2013, now 26 of 33]. But that is a deceptive statistic because in most of these years the winner wrapped up the Series in fewer than seven games—indeed, the losing club in a five-game Series that commenced in the opponents’ city will have had three games at home.

The ultimate World Series thrill has to be winning at home in a seventh game. And in a seeming repeal of the rules of probability, the home team has won Game 7 in each of the last nine World Series that went the distance (the first in 1982, the most recent in 2011).

What’s going on here? Some have laid responsibility at the Commissioner’s feet, for rewarding the All-Star Game winner with home-field advantage, but that decision came in 2003 so clearly is not the answer. The long-established home-field advantage in any one game is 54-46—in other words, the host club may be expected to win any particular game 54 percent of the time. Yet when the home-field advantage is distributed across four games, it diminishes to 51 percent. So what are we to make of the fact that—again, since 1980—the home team in the World Series has won 109 of 175 contests, a winning percentage of .623?

As has long been my custom, when presented a puzzle beyond my understanding, I consulted with old friend and collaborator Pete Palmer. The sample size of World Seriessince 1980, he pointed out, led us to a calamitous conclusion—the sky is falling!—by conveniently lopping off the years 1950-1979, during which the home team lost the seventh game 12 of 15 times (!).

“The actual World Series home team winning perecentage,” Pete said, “is 55 percent,” counting all games since 1903. “But for some reason, the rate since 1969 is significantly higher at 61 percent, even though the divisional series is 52 percent and the championship series 54 percent. And over a seven-game series, that 61 percent translates to only 52 percent overall: 3 [games] x .39 + 4 [games] x .61) / 7.

“So,” Pete concluded, “it would appear the home team advantage in the World Series is minimal.”

Alarmists inclined to jump out the window are advised first to confirm that they are on the ground floor.