from Baseball Prospectus:
The Daily Prospectus: One Up
by Joe Sheehan
Yesterday, the Braves, Indians, and Diamondbacks took an important first step towards advancing by winning the opening game of their respective series. How big a step? In the 24 Division Series played to date, the winner of the first game has gone on to win 16 times. That's two-thirds of the time, 66.7%.
The biggest story, of course, is the Indians, who upset the 116-46 Mariners in Seattle behind Bartolo Colon's eight shutout innings. The Braves also won on the road, thanks to a Chipper Jones three-run home run. I thought the Indians had a shot to steal their series, and winning yesterday puts history on their side: teams that open the Division Series with a road win are 7-3.
Looking back a bit further, teams that opened with a win in the five-game League Championship Series (1969-1984) were 22-10. Teams that opened with a road win were 11-4.
Let's put those together to see, independent of team quality, how the Mariners/Indians (and Braves/Astros) series changed yesterday. The following table covers all MLB five-game postseason series (save the 1981 first round).
Road Team Home Team
Wins Game One Wins Game One
1969-1984 11-4, .733 11-6, .647
1995-2000 7-3, .700 11-5, .688
Total 18-7, .720 22-11, .667
Had the Mariners won yesterday, history would give them a two-thirds chance of winning the five-game series. Now, having lost, they're staring at bucking a serious trend: more than seven times out of ten, a home team that loses the first game goes back home to stay within a week.
This isn't a perfect tool--I mean, teams that win at least 114 games are 1-0 in Division Series play--but it does indicate just how important that win was for the Indians.