“In Syracuse they say Jack Humphreys is the prettiest grand-stand player in the state league.” Rochester Democrat and Chronicle, August 9, 1885, p7
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. 1886. “[Kid] Baldwin of the Cincinnatis, has the credit of being the greatest grandstand player” (The Sporting News, May 24; David Shulman).