“A’s Flatten KC–A ‘Billy Ball’ Blitz” (Headline). “For the casual A’s fan — and one must assume that most of them fit that description — yesterday’s game at the Coliseum was a classic example of what Billy Martin baseball is all about. ‘Billy Ball,’ as they say, is making the most of your talent, and what the A’s do best is run.” Bruce Jenkins. San Francisco Chronicle, May 29, 1980, p59 [Ken Liss]
NOTE: According to an April 17, 1981 column by Glenn Schwarz in the San Francisco Examiner Ralph Wiley introduced the term in an Oakland Tribune column on March 23, 1980.
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
The term was introduced as one word (“Billy-ball”) by Oakland Tribune sportswriter Ralph Wiley in 1981 when Martin was manager of the Oakland Athletics.