[doikor]

> Doesn’t seem like much more of an advantage than people yelling things at baseball players?

The baseball equivalent would be the crowd knowing signals between the pitchers and catcher and yell them out so the batter always know what pitch is coming. (this is pretty much the only hidden information in baseball)

That would pretty much ruin the game (in some players/fans mind at least). And in fact this is something the MLB is actively trying to solve by providing encrypted signal communication devices so players don't have to rely on finger/etc signals that can be decrypted by the opposing team.