“It’s not how big you are, it’s how big you play” is a sports adage that has been used in several sports. The saying has been cited in print since at least 1967, when it was used by Northwestern University football coach Alex Agase (1922-2007). In 1968, this was called one of Agase’s favorite sayings, Agase credited the saying to his coach at the University of Illinois in 1941, Ray Eliot (1905-1980),
   
“It’s not how big you are that counts, it’s how big you play” was credited in 1971 to UCLA basketball coach John Wooden (1910-2010), who won a national championship in 1964 with an undersized team. Wooden’s 1964 use of the saying has not been verified in print.
     
 
Wikipedia: Ray Eliot
Raymond Eliot Nusspickel (June 13, 1905 – February 24, 1980) was an American football and baseball player, coach, and college athletics administrator. He served as the head football coach Illinois College from 1933 to 1936 and at the University of Illinois at Urbana–Champaign from 1942 to 1959, compiling a career college football record of 102–82–13. Eliot was also the head baseball coach at Illinois College from 1933 to 1937. His Illinois Fighting Illini football teams won three Big Ten Conference championships (1946, 1951, and 1953) and two Rose Bowls (1947 and 1952). Eliot, who spent almost his entire career at the University of Illinois—he was a student athlete, an assistant football coach, head football coach, associate athletic director, and finally the interim athletic director for the university—was nicknamed “Mr. Illini.” He attended the University of Illinois, played as a guard on the football team in 1930 and 1931, and was a member of Alpha Sigma Phi fraternity.
 
20 December 1963, Chicago (IL) Tribune, “In the Wake of the News” by David Condon, sec. 3, pg. 1, col. 1:
“Ray Eliot was the greatest of them all,” Agase says today.
 
Eliot took a few seconds to size up Agase, and then Ray said in his patent paternal manner: “Son, it’s not how big you are—it’s how big your heart is.”
 
“The remark he made to me is the most significant thing in my football life,” says Agase, grown into a 220-pound barrelhouse who has ha a barrel of success in the game.
   
20 March 1967, The Arizona Republic (Phoenix, AZ), “Indy Pays Tribute To Owen J. Bush” (AP), pg. 2-E, col. 6:
“I used to tell ‘em it ain’t how big you are, it’s how good you are,” (baseball shortstop—ed.) Bush recalls.
 
29 October 1967, Rockford (IL) Morning Star, “Anstey Makes Good On Big Opportunity” by Rick Talley, pg. C-2, col. 7:
“It’s not how big you are…It’s how big you play,” he (Northwestern University football coach Alex Agase—ed.) said.
 
18 October 1968, Daily Northwestern (Evanston, IL), “Determination fires Kurzawski” by Andy Lippman, pg. 10, col. 4:
Even though he is often at the bottom of a pile of huge lineman, Chico K——ski bounces back time after time—proving one of Agase’s favorite sayings, “It’s not how big you are that is important, it’s how big you play.”
 
17 February 1971, The Arizona Republic (Phoenix, AZ), “Western is host to Mesa” by Dick Smith, C-3, col. 1:
“It’s like UCLA’s coach Johnny Wooden said when he had that great little team (1964) that won the national championship,” mused Arizone Western basketball coach John Whisenant.
 
“‘It’s not how big you are that counts…it’s how big you play…’” said Whisenant, whose words were in praise of state league leader Mesa Community College.
 
21 March 1971, The Sunday Oregonian (Portland, OR), “Pels Head Title List” by Bob Robinson, Sports sec., pg. 7, cols. 7-8:
But, then he (Lion Coach Ernie McKie—ed.) grinned, winked and added: “But it is not always how big you are that counts; it is how big you play.”
       
Google Books
Ray Eliot:
The Spirit and Legend of Mr. Illini
By Doug Cartland
Champaign, IL: Sagamore Publishing
1995
Pg. 52:
He reminded them that it was “not how big you are, but how big you play.”
 
Google Books
Preaching Proverbs:
Wisdom for the Pulpit
By Alyce M. McKenzie
Louisville, KY: Westminster John Knox Press
1996
Pg. 84:
“It’s not how big you are. It’s how big you play.”
 
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It is not how big you are, it’s how big you play. - Unknown
10:03 PM - 1 Dec 2015
 
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It is not how big you are, it’s how big you play. -Unknown
3:19 PM - 3 Dec 2015