"There is an old adage that says a game is never out till it is played out" was cited in a Kansas newspaper in 1892. No particular person has been credited for the adage.
Baseball player and manager Yogi Berra (1925-2015) is often credited with, "It ain't over 'til it's over." The circumstance was 1973, when Berra was the New York Mets manager and saw the team come from behind in a crowded field to win the National League East pennant. This exact quote hasn't been found, but Berra did say in September 1973:
"Yeah, it's running out, but you're still not out of it until it's automatic."
Related sayings include “Church is never out until they stop singing,” “The rodeo ain’t over till the bull riders ride” and “The opera ain’t over until the fat lady sings."
[This entry includes research from the Quote Investigator.]
11 April 1892, Lawrence (KS) Daiy Journal, pg. 2, col. 1:
THERE is an old adage that says a game is never out till it is played out. This applies as well to politics as to seven up.
4 September 1973, New York (NY) Post, "Time Running Out on Mets," , pg. 64, col. 1:
"Yeah, it's running out, but you're still not out of it until it's automatic," Yogi Berra revealed late yesterday afternoon.
30 June 1974, New York (NY) Times, "A 'Character' Named Berra" by Red Smith, pg. 191:
He is not yet ready to admit that this year's Mets can't repeat. "You're not out of it," he insisted recently, "until you're out of it."
6 September 1977, Washington (DC) Post, pg. D2:
"It's not over," Pirate manager Chuck Tanner insisted after the split. "Things can turn around in a week in baseball. It's over when the numbers say it's over."
23 August 1979, New York (NY) Times, pg. B11:
"It's never over until it's over," Yogi Berra once said.
April 02, 1984
As a reincarnated Yankee skipper, Yogi Berra is working for George Steinbrenner. Is Yogi worried about longevity? No. He knows a managing job, like a ball game, ain't over 'til it's over
Roy Blount Jr.
Research through old sports-page clippings indicates that what Berra probably said was, in reference to the 1974 pennant race, "We're not out till we're out." That quickly became "You're not out of it till you're out of it," which somehow evolved into "The game's never over till it's over," which eventually was streamlined into "It ain't over 'til it's over."
But I wouldn't call that a wholly manufactured product. Berra sprouted its seed. And he did so at a time when the expression "The game is never over till the last man is out" had become hackneyed, even if its meaning still held true. One thing Berra doesn't deal in is clichés. He doesn't remember them.
New York (NY) Times
By WILLIAM SAFIRE
Published: February 15, 1987
I have long been searching for the origin of ''The opera ain't over till the fat lady sings.'' Coach Dick Motta of the Chicago Bulls, who popularized the phrase in 1978, has been noted here as a possible coiner, but Daniel S. Knight of Philadelphia, who styles himself spokesman for the ''Fat Lady Sings Society,'' cites the Concise Oxford Dictionary of Proverbs: In 1975, Ralph Carpenter, information director of Texas Tech, told a contingent of sportswriters in the Austin press box that ''The rodeo ain't over till the bull riders ride.'' Dan Cook, a sports editor for The San Antonio Express-News, responded with ''The opera ain't over till the fat lady sings.''
In searching for the origin of this gem, I came across the simpler and even more frequently cited ''It ain't over till it's over,'' which I presume is a shortening (and philosophic extension) of the adage ''The ball game isn't over until the last man is out.''
Did Yogi Berra actually say that, or was it a concoction of some anonymous attributer? Reached at his Montclair, N.J., home, Mr. Berra acknowledges the coinage: ''Yes, I said that. It was during a pennant race for the Mets.''