“You boys line up, alphabetically according to your height” is nonsensical sports coach-speak—a player line rarely can be both alphabetical and also by height. Ed Diddle (1895-1970), a basketball coach at Western Kentucky and one of the winningest coaches in college basketball history, was reported in 1955 to have once told his players:
 
“I want you boys to line up alphabetically and according to height!”
 
Fred Russell’s book, Bury Me In An Old Press Box; Good Times and Life of a Sportswriter (1957), recorded about Diddle:
 
“Or in passing out new varsity jerseys: ‘You boys line up, alphabetically according to your height.’”
 
The line has been usually credited (since 1982) to New York Yankees and New York Mets baseball manager Casey Stengel (1890-1975), but this is far later than printed citations crediting Diddle.
 
   
Wikipedia: Edgar Diddle
Edgar Allen Diddle (March 12, 1895 – January 2, 1970) was an American college men’s basketball coach. He is known for coaching at Western Kentucky University in Bowling Green, Kentucky from 1922 to 1964. Diddle became the first coach in history to coach 1,000 games at one school. Diddle was known for waving a red towel around along the sidelines during his games. He was known to wave, toss, and chew on this towel, and even cover his face in times of disappointment. His red towel is now part of WKU’s official athletic logo. Diddle experienced only five losing seasons in 42 years and overall, averaged 25 wins per year. He was born in Gradyville, Kentucky.
 
Diddle’s teams claimed 32 conference championships, played in 11 postseason tournaments; won 20+ games eighteen different times, (including one stretch of ten years in a row); became the first team from the South to participate in the Olympic Trials; and won an amazing 759 games. When he stepped down in 1964 Diddle had won more games than any coach in NCAA history and today he still ranks in the top ten on the all-time list.
 
Google News Archive
22 May 1955, Park City Daily News (Bowling Green, KY), “Western Kentucky Basketball Coach Ed Diddle To Speak At Breakfast,”  pg. 10, col. 2:
Or about the opening day of practice: “I want you boys to line up alphabetically and according to height!”
 
Google Books
Bury Me In An Old Press Box;
Good Times and Life of a Sportswriter
By Fred Russell
New York, NY: Barnes
1957
Pg. 88:
Or in passing out new varsity jerseys: “You boys line up, alphabetically according to your height.”
(Western Kentucky basketball coach Ed Diddle—ed.)
   
29 December 1959, The Times-Picayune (New Orleans, LA), “Diddle’s Dandy Antics,” sec. 2, pg. 9, col. 2:
The mention of Western Kentucky always brings to mind the many humorous tales oft repeated about WK’s coaching wizard, Ed Diddle.
(...)
Here are a few we remember from reading Freddie Russell’s book, “Bury Me in an Old Press Box”:
(...)
2—While passing out new uniforms: “You boys line up alphabetically according to your height.”
     
Sports Illustrated
January 11, 1960
Events & Discoveries
Edgar Allen Diddle was born on a farm in Gradyville, Ky. in 1895.
(...)
Between games he keeps his boys alert with verbal twists. He’s been known to ask his squad to “Line up alphabetically according to height.”
 
Google News Archive
31 March 1982, Ocala (FL) Star-Banner, sports editor Bud Crussell’s column, pg. 1D, col. 1:
And, the one by Casey Stengel, “All right, everyone, line up alphabetically according to your height.”
(From Baseball’s Greatest Quotes, edited by Kevin Nelson—ed.)
 
Google Books
Joe DiMaggio:
A Biography
By David Jones
Westport, CT: Greenwood Press
2004
Pg. 109:
Though Stengel did contribute many humorous sayings, or “Stengelese,” to the lexicon — “All right everybody,” he once instructed his team, “line up alphabetically according to your height” — he also possessed a keen analytical mind.
 
Google Books
Get ‘Em Laughing:
Public Speaking Humor, Quotes and Illustrations
By E. Gene Davis
Victoria, BC: Trafford Publishing
2007
Pg. 209:
Here are some examples:
“All right everyone, line up alphabetically according to your height.”
Casey Stengel, New York Yankee manager