How Do You Know if You're Considering Hiring a Head of Operations?

How far off is this internal person from having the exact experience necessary to be perfect for the head of operations rule? How good are they at critical thinking and having a strong work ethic so they can learn things they don't already know? Can we afford the time to allow the internal person to ramp up? Or no, said differently, how mission critical is this person's roll within the company's strategy? And how much will our goals and company moral suffer if we cannot execute on the time line that we wanted? So ultimately, when you end on making this decision, you're basically just deciding what trade offs or unknowns that you're willing to live with for an external hire.