ON ACTING: The Obligation of the Teacher or Director
When a would-be patient visits the doctor’s for a medical check-up, the patient rightfully expects the doctor (by intuition, eye or by instrument) to clearly evaluate the patient’s health, to recognize any symptoms of illness, and if there are symptoms, diagnose the underlying disease; and then to proscribe remediation (pills, et. al.).
A patient would be rightfully aghast is the doctor just said: “You’re sick,” charge a fee and left it at that.
Unfortunately, I’ve known more than a few acting teachers and directors do precisely that when evaluating an actor's 'ill' performance in class or on set.
When an actor's performance is 'ill', the director (or acting teacher) is responsible to offer corrective help. They cannot just say the performance is 'ill'..."I don't like it"...they must (if they are any good themselves!) help the actor specifically recognize bad acting symptoms, understand and analyze the causes of the acting performance/illness manifested by those symptoms, and guide the actor to taking corrective and remedial action to attain good performance health.
A teacher or director who does anything less is a lesser teacher and/or director.