I recently acquired a copy of the 1913 edition of Spalding's Official Baseball Guide, and in it, there is some talk of a new statistic for evaluating pitchers beyond pitcher wins. Though it doesn't have the name just yet, the statistic is clearly ERA:
In the new record for pitchers, which has been established this season by Secretary Heydler of the National League, and which in part was the outcome of the agitation in the GUIDE for a new method of records, in which the various Base Ball critics of the major league cities so ably contributed their opinions, Tesreau leads all the pitchers in the matter of runs which were earned from his delivery. Mathewson is second, Ames is fifth, Marquard seventh and Wiltse and Crandall lower, and while both the latter were hit freely in games in which they were occasionally substituted for others, they pitched admirably in games which they won on their own account.
In the opinion of the writer this new method, which has been put into usage by Secretary Heydler, is far superior to anything which has been offered in years as a valuable record of the actual work of pitchers. It holds the pitcher responsible for every run which is made from his delivery. It does not hold him responsible for any runs which may have been made after the opportunity has been offered to retire the side, nor does it hold him responsible for runs which are the result of the fielding errors of his fellow players. On the other hand, if he gives bases on balls, if he is batted for base hits, if he makes balks, and if he makes wild pitches, he must stand for his blunders and have all such runs charged against him as earned runs.
Nothing proves more conclusively the strength of this manner of compiling pitchers' records than that Rucker, by the old system, dropped to twenty-eighth in the list of National League pitchers, finished third in the earned run computation, showing that if he had been given proper support he probably would have been one of the topmost pitchers of the league, even on the basis of percentage of games won, which is more vainglorious than absolutely truthful.