> Not hard at all. Baseball, from juniors to the majors, also uses sign language.

This need additional contexts. Deaf communities use Signed Languages in baseball. Outside of Deaf communities, they are not sign language. Language by definition requires grammar structure, cultural information, foundation of linguistic, etc.

They are using pidgin is the word you are looking for. Baseball use pidgins, they don't use sign languages. It is an important distinctive because one is actual language and other are not.