The term 'play callers' refers to umpires, who are responsible for making decisions on the field during a baseball game. Umpires are responsible for calling balls and strikes, as well as making other rulings such as fair or foul balls, safe or out calls, and other judgement calls. Umpires must also enforce the rules of the game, and have the authority to eject players or coaches from the game if necessary. Umpires are an integral part of the game, and their decisions can have a major impact on the outcome of the game.