 An associate described Croker as having "[a] strong frame, a deep chest, a short neck and a pair of hard fists...He speaks in monosyllables, [and] commands a vocabulary that appears to be limited to about three hundred words..."

Croker operated a stable of thoroughbred racehorses in the United States in partnership with Mike Dwyer.In January 1895, they sent a stable of horses to England under the care of trainer Hardy Campbell, Jr. and jockey Willie Simms.