The principle just requires that competence at job A doesn't guarantee competence at the job you are promoted to after A. You would get the same results if comp

The principle just requires that competence at job A doesn't guarantee competence at the job you are promoted to after A. You would get the same results if competence at a job were random. Notably it also suggests people could be great at high level jobs but never reach them because they aren't good at the low level ones.