A mentor is typically someone who has been in the role before. You go to him for advice or they can give you their perspective/ experience about things
A coaching relationship is different. They hold space for you, ask questions to help you figure out what’s best for you.
When judging people for leadership positions, or for jobs that require strongly synthetic abilities, you should consider how well they are capable of generating an understanding of context across a broad range of domains, including ex nihilo, so to speak.
When something isn’t getting done, it’s because the person a) doesn’t have the time b) doesn’t have the skill or c) has some sort of psychological block. The third case is surprisingly common.