The idea of middle managers as unexceptional, mediocre supervisors has been around for decades — at least since a seminal 1977 HBR article by Abraham Zaleznik that made a clear, explicit distinction between being a leader (an inspirational visionary) and a manager (a strategic administrator). These ideas are still central to what’s taught in many MBA and executive development programs, where there’s a tendency to educate managers on how to “upgrade” and become leaders.