Original: In the book The Neyer/James Guide to Pitchers, sports journalist Rob Neyer wrote that the speed with which pitchers like Cy Young, Amos Rusie, and Jouett Meekin threw was the impetus that caused the move.
Simplified: In the book The Neyer/James Guide to Pitchers, sports journalist Rob Neyer wrote that the reason for the move was that pitchers like Cy Young, Amos Rusie, and Jouett Meekin threw too fast at the shorter distance.