Whether an internal promotion or an external hire, adapting can be a challenge.
The transition from tactician to strategist is a transition best not made alone. Similarly, being the new leader from outside is a challenge that should be supported.
A promotion brings many diverse challenges. Each individual situation comprises the development of new skill sets, new communication styles and moving from the tactical to the strategic mindset; the transition of moving from a position and skill set in which one had constantly and traditionally been able to demonstrate tremendous value, to a new area of responsibility.