Bill James and Rob Neyer have been two who have stated it was not Stricklett who invented the pitch. Reportedly, Elmer never claimed to have invented the pitch himself; he did claim to have mastered the pitch. Two pitchers he taught the pitch to: Ed Walsh and Jack Chesbro, would make it into Baseball's Hall of Fame. Stricklett learned the pitch from minor league teammate George Hildebrand in 1902.
Hildebrand learned the pitch, supposedly, from Frank Corridon, who pitched in the big leagues from 1904-1910. Corridon apparently picked up a ball out of a puddle and saw that the ball was wet on one side of it. After throwing the ball, he noticed that it had a different type of flight to the ball and was able to move differently. He experimented with it and was able to hold on to a decent MLB career, strictly by throwing that pitch.
The definition of the spitball, according to wikipedia.org, is a baseball pitch, in which the ball has been altered by the application of saliva, petroleum jelly or some other foreign substance. By the 1910s, the pitch had become common with pitchers using everything from saliva to blood to tobacco juice to mud to doctor the baseball. Some had stated it was a dangerous pitch, since the pitcher did not necessarily have control over where it was going. In 1920, Red Sox RHP Carl Mays hit Indians SS Ray Chapman in the temple, where Chapman would later die from complications. Mays threw a spitball that got away from him. At the time, the Baseball Commission was phasing the pitch out of the game. It had decided that for the 1920 season, the pitch would be limited to two pitchers per team, who had to be designated. After the 1920 season, the pitch would be outlawed, except for the pitchers who were grandfathered in. These pitchers would be allowed to throw the pitch until their careers were over. The last pitcher to legally throw the pitch was Brooklyn RHP, among other teams, Burleigh Grimes, who would pitch until the 1934 season. Among other pitchers to be allowed to throw the pitch were Urban Shocker, Dutch Leonard and Red Faber.