I have watched this happen often enough that I no longer find it surprising, only worth explaining properly, because the reasons behind it are rarely the same from one person to the next, even though the pattern looks identical from the outside.
For some people, it is simply a skill gap nobody named out loud. Being excellent at a task and being excellent at developing other people in that task are genuinely different abilities, and very few organisations train for the second one before handing someone the title that requires it.
For others, it is an identity shift they were never prepared for. As an individual contributor, your job is to be understood by one supervisor. As a manager, your job is to be understood by people with less context, less experience, sometimes less confidence, and that asks for an entirely different kind of patience, one many strong performers have simply never had to practice.
"Managing is not doing the work through other people. It is helping other people become capable of doing the work themselves."
For some, the struggle is really about control, quietly disguised as high standards. A person who has always trusted their own instincts most finds it genuinely hard to watch someone else learn slowly, and their impatience often gets mistaken, even by themselves, for simply caring about quality.
And for others, honestly, the promotion was simply the wrong fit to begin with. Not every excellent individual contributor wants to manage people, or is energised by it, and organisations sometimes hand out management titles as the only visible reward for excellence, when what that person actually needed was recognition, not a team.
Underneath most of these, though, sits something more personal that is worth naming. Many new managers have never been asked to examine their own leadership identity, their habits under pressure, what accountability actually feels like when it is theirs to hold rather than someone else's. Without that groundwork, whichever of these gaps is at play tends to stay stuck, because the training being offered is usually aimed at the surface symptom, not the actual cause underneath it.
If you are watching a strong employee struggle in a new leadership role, it is worth sitting with them long enough to find out which of these is actually happening, rather than assuming it is only one thing, or worse, assuming it is simply a bad fit and moving them back without ever finding out.
This is one of the questions we hear often through our Leadership and Management Development work at Potential Unexplored Ltd. Visit our Leadership and Management Development page to learn more, or get in touch to talk through what your team needs.