Baseballese (1897)

“The departure of the ‘Colts’ for their winter training at Hot Springs reminds the public that in due time the talented chroniclers of our national game will again drop into that highly picturesque form of speech that might be called baseballese … It’s no small art to write baseballese.” The Daily Inter Ocean [Chicago], March 12, 1897, p6

Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1912. “Some writers call it ‘baseballese’ you call it either one you please.” Edmund Vance Cooke, Baseballogy