The result of various Supreme Court cases is that some speech is more clearly of public concern than others. Matters of elections, pending legislation, corruption, race discrimination, public health and safety are in the zone of public concern. Matters of internal employment policy that do not touch on these public concerns are normally unprotected.
Other matters may or may not be of public concern, depending on the scope of media attention, controversy, or, on the other hand, how deeply they disrupt the function of the public office. Sometimes we just cannot tell what a court will do with a case raising a new area or an issue that raises strong concerns about both public policy and internal disruption. As the Supreme Court stated in Connick v. Myers:
Whether an employee's speech addresses a matter of public concern must be determined by the content, form, and context of a given statement, as revealed by the whole record.