“Reports from the Senators’ training camp at Tampa, Fla, state that George Mogridge has been perfecting a ‘hesitation’ ball, such as Howard Ehmke and Johnny Cooney used at times last season.” Ford Sawyer, “Baseball Pickups from Major Training Camps,” Boston Globe, March 24, 1925, p18
“In the first game Johnny Cooney the lefthander with a hesitation pitch, humiliated the Giants with a three-hit performance.” “Recruit Pitcher Stars in First Start for Giants,”The Gazette (Montreal), August 17, 1925, p14 (Headline refers to first game of doubleheader; Cooney pitched second game)
NOTE: There are some earlier uses of the term “hesitation ball,” but these seem to be largely fanciful or metaphorical uses not referring to an actual pitch.
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
The Dictionary does not list a first use but says that the pitch was developed by Satchel Page in the Negro Leagues.