“The playoffs don’t start until the home team loses a game” (or “No playoff series truly begins until the road team wins a game”) is an old NBA saying. NBA coach Pat Riley popularized the saying in the 1980s, but it is not known who said it first. The “home team loses” version appears to be earlier than the “road team wins” version.
     
“‘As the theory goes, the playoffs don’t really start until the home team loses a game,’ he (Los Angeles Lakers coach Pat Riley—ed.) said” was printed in the St. Petersburg (FL) Times on May 29, 1983. “However, he (Pat Riley—ed.) said the playoffs never start until the home team loses, so the current best-of-seven series only started yesterday” was printed in the Hawaii Tribune-Herald (Hilo, HI) on May 21, 1984.
     
“Conventional wisdom says a playoff series doesn’t really start until the road team wins a game” was printed in the Rocky Mountain News (Denver, CO) on June 7, 1997. “They always say a playoff doesn’t start until the road team wins a game” was printed in the Quad-City Times (Davenport, IA) on April 12, 1998.
   
The saying has also been used in professional baseball and hockey.
     
       
Wikipedia: Pat Riley
Patrick James Riley (born March 20, 1945) is an American professional basketball executive and a former coach and player in the National Basketball Association (NBA). He has been the team president of the Miami Heat since 1995, and he also served as the team’s head coach from 1995 to 2003 and again from 2005 to 2008. Regarded as one of the greatest NBA coaches of all time, Riley has won five NBA championships as a head coach, including four with the Los Angeles Lakers during their Showtime era in the 1980s and one with the Heat in 2006.
   
Newspapers.com
29 May 1983, St. Petersburg (FL) Times, “&6ershoping to keep Laker’s backs pressed against the wall” by Mike Tierney, pg. 8C, col. 3:
“As the theory goes, the playoffs don’t really start until the home team loses a game,” he (Los Angeles Lakers coach Pat Riley—ed,) said.
   
Newspapers.com
21 May 1984, Hawaii Tribune-Herald (Hilo, HI), “Lakers move a step close in West finals” (UPI), pg. 6, col. 2:
Riley said the Lakers, aiming for their third title in five years, “have the momentum.”
 
However, he said the playoffs never start until the home team loses, so the current best-of-seven series only started yesterday
 
Newspapers.com
28 May 1984, The Sun (San Bernardino, CA), “Who needs rest? Lakers put Celtics to sleep” by Steve Dilbeck, pg. C-5, col. 4:
Riley likes to say the playoffs don’t start until the home team loses.
 
Google News
5 June 1987, Lodi (CA) News-Sentinel, “Lakers rout Celtics again” (UPI), pg. 16, col. 5:
”(Someone) said the playoffs don’t start until the home team loses at home,” said Lakers Coach Pat Riley, whose team is 9-0 in the Forum.
 
7 June 1987, Atlanta (GA) Journal and Constitution, “Magic tricks stolen’ from greats of game.” pg. D3:
But Pat Riley, quoting from Phoenix columnist Joe Gilmartin, says, “A championship series hasn’t started until the home team loses or the seventh game.
     
New York (NY) Times
Sports of The Times; Why Rockets Fear a Triple Play
By GEORGE VECSEY
Published: June 12, 1994
(...)
“The playoffs don’t get interesting until the home team loses,” Riley (New York Knicks basketball coach Pat Riley—ed.) said, and he should know. He has been there seven times before. He attributed that piece of wisdom to Joe Gilmartin, the sage of The Phoenix Gazette.
 
“Pat’s used that quote for the last 10 playoffs,” Gilmartin said Friday, “but he’s strayed a little from my original line. What I said was, ‘The playoffs don’t begin until the home team loses—or the seventh game.’ “
 
7 June 1997, Rocky Mountain News (Denver, CO), “Malone Delivers for Jazz” by Dave Krieger:
Conventional wisdom says a playoff series doesn’t really start until the road team wins a game. By that measure, this series still isn’t under way.
 
Newspapers.com
12 April 1998, Quad-City Times (Davenport, IA), “Skyforce ‘steal on on road’” by Craig DeVrieze, pg. 10S, cols. 4-5:
“They always say a playoff doesn’t start until the road team wins a game.”
(Sioux Falls coach Mo McHone.—ed.)
     
Newspapers.com
9 October 1998, Daily News (New York, NY), “A Win Is Best Way To Forget” by Mike Lupica, pg. 94, col. 2:
Jeff Van Gundy, the Knicks coach, always says the series doesn’t start until the road team wins a game. The road team has won a game now.
   
Google Books
Reversing the Curse:
Inside the 2004 Boston Red Sox
By Dan Shaughnessy
Boston, MA: Houghton Mifflin
2005
Pg. 103:
An old saying in the National Basketball Association holds that no playoff series has truly begun until the road team wins a game.
     
axcentral.com blogs
Bob Young
Monday, May 12, 2008 at 06:58 PM
We’ve only just begun
As the NBA playoffs have unfolded, perhaps you’ve heard some of the talking heads refer to the NBA axiom that a playoff series “doesn’t start until the home team loses.”
 
Of course, that means that through the weekend we were still waiting for the second round to start because no road team had broken through.
 
Former Miami/New York/Los Angeles coach Pat Riley used to refer to that axiom almost every time he was in the playoffs.
 
He called it “The Joe Gilmartin Rule.”
 
That’s because Gilmartin, longtime columnist for the now-defunct Phoenix Gazette, who still writes for Suns and Diamondbacks publications, first made that observation in the heyday of the Lakers-Celtics rivalry in the 1980s.
 
Yardbarker.com
Down 0-2 to Boston, it’s win-or-else time for Heat
Found April 21, 2010 on Boston.com:
Dwyane Wade likes to say that no playoff series truly begins until the road team wins a game.
   
Ace of Spades HQ
June 15, 2011
Stanley Cup Final Game 7
8 eastern on NBC.
 
The old saying in any sport is no playoff series begins until the road team wins a game. Apparently this series has yet to begin. Each team has won the 3 games on their home ice. Boston blew out the Canucks 3 times in Boston, while the Canucks have held on to win 3 1 goal games in Vancouver.