“A full mind is an empty bat” (baseball adage)

Baseball players hitting in the batter’s box often think too much, resulting in poor performance.” “A full mind is an empty bat” is a saying that has been credited to baseball executive Branch Rickey (1881-1965), but it’s not known when he said it. “A full mind is an empty bat” was credited to Rickey in 1975 and “‘A full head makes for an empty bat” was credited to Rickey in 1976. The expression is sometimes shorted to “full head, empty bat.”
 
“When you think, you stink” and “You can’t think and hit at the same time” are related sayings.
 
   
Wikipedia: Branch Rickey
Wesley Branch Rickey (December 20, 1881 – December 9, 1965) was an innovative Major League Baseball executive elected to the Baseball Hall of Fame in 1967. He was known for breaking Major League Baseball’s color barrier by signing African American player Jackie Robinson, for drafting the first Afro-Hispanic superstar, Roberto Clemente, for creating the framework for the modern minor league farm system, for encouraging the Major Leagues to add new teams through his involvement in the proposed Continental League, and for introducing the batting helmet.
 
28 July 1975, New York (NY) Times, “Virdon’s Job Is ‘a Precarious Job’” by Dave Anderson:
Branch Rickey used to say, “A full mind is an empty bat.”
 
18 October 1976, The Courier (Findlay, OH), “Yankee Hanky-Panky With Walkie Talkie Drives Cincinnati Batty” (AP), pg. B1, col. 5:
“I remember Branch Rickey’s adage, ‘A full head makes for an empty bat.’”
(Gabe Paul, president of the New York Yankees—ed.)
 
3 June 1979, The Plain Dealer (Cleveland, OH), “Hitters born, not made” by Bob Dolgan, sec. 3, pg. 3, col. 1:
Paul (Gabe Paul, president of the Cleveland Indians—ed.), incidentally, uses one of his favorite expressions to explain why the Indians aren’t hitting. “A full head means an empty bat,” he said, meaning that his braves are thinking too much, that their brains are full of heavy theory.
   
Google Books
Sportswit
By Lee Green
New York, NY: Harper & Row
1984
Pg. 80:
BRANCH RICKEY
St. Louis Cardinals general manager:
“A full mind is an empty bat.”
 
Google Books
Men at Work:
The Craft of Baseball
By George F. Will
New York, NY: Macmillan
1990
Pg. 210:
Branch Rickey, who had as full a head as has ever been put in the service of baseball, said: “Full head, empty bat.”
     
Rivals.com
May 2, 2008
Nate Trosky (Carmel-Baseball.com)
Mental Game Series: AN EMPTY HEAD = A FULL BAT
(...)
“A Full Head Equals an Empty Bat,” is a quote from Branch Ricky, one of the greatest baseball minds in the history of the game.
 
Google Books
Just Play Ball
By Joe Garagiola
Flagstaff, AZ: Northland Pub
2009
Pg. 202:
I remember the way he summed up a batter who he felt was thinking too much in the batter’s box. Mr. Rickey simply said, “Full mind, empty bat.” That other great philosopher, Yogi Berra said, “You can’t hit and think at the same time.” Different words, different school, but the same result.
 
Twitter
Lauren Chamberlain
‏@LChamberlain44
“A full head is an empty bat”
7:49 PM - 17 Feb 13
   
The Oregonian (Portland, OR)
College World Series: Oregon State won’t advance until Dylan Davis relaxes and produces
By Jason Quick
on June 18, 2013 at 2:08 PM, updated June 18, 2013 at 7:39 PM
(...)
“It’s like that old saying: Empty head, full bat. Full head, empty bat.”