This is too broad and general of a statement to make. Depending on the size of the organization, the work you're trying to do, the pipeline and network of employees you've worked with at other places, bringing in a leader from outside not only could be important for growing the company in a new direction but also provide an outside and objective perspective on a team that isn't performing. I have seen managers promoted from within with negative results and brought in from outside with great success. Don't remove a tool from your toolbelt as a leader unnecessarily.
