Luck Of The Draw Meaning

Example : 1973, Sheila Sutcliffe, Martello Towers, ISBN 9780838613139, p. 63:  [A] dry ditch or moat . . . should have been constructed around towers in particularly exposed or vulnerable positions but in some cases it seems that they were selected by the luck of the draw.1996 May 21, Carey Goldberg, "Best-Selling Author, but Not at Home," New York Times (retrieved 8 June 2013):  [I]s it merely the luck of the draw that turns some novels into blockbusters and others of equal merit into also-rans?2005 August 10, "What You Need to Know on Smoking and Lung Cancer," Time:  If you've never been a smoker and you develop lung cancer, how did you get it? Is it genetics, environment, radon, luck of the draw?