“The only correct methods of arriving at the capabilities of a player is to consult his standing in the batting and fielding averages for the entire season. The players know this, and they also know that every first-base hit, and every game played without fielding errors, enhance their values with regard to future engagements.” “Games and Pastimes,” Chicago Tribune, September 24, 1871, p3
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
An early fielding statistic, calculated by dividing putouts plus assists by games played, devised by Philadelphia baseball writer Al Wright in 1875 (John Thorn and Pete Palmer, The Hidden Game of Baseball, 1985). It is identical to range factor. “The men having the best and poorest fielding average in the various positions were as follows.” (Chicago Tribune, July 11, 1880; Peter Morris).