Sometimes these are measurable and are called physical capacity tests. Sometimes, as with motion palpation of accessory movement of a joint, they are not measurable and are referred to as dysfunctions. Other examples of deconditioning involve various skills or tasks such as lifting, carrying, climbing, balancing, etc. If rehabilitation is concerned with restoration of function, then by definition it would include both passive and active care. Manipulation of a joint to restore mobility is just as much rehabilitation as back extensor exercises are.
Rehabilitation encompasses both passive and active care.
Generally, in acute care, treatment focuses on stabilization, pain relief and promotion of tissue healing. Once a patient can safely tolerate normal activities of daily living, pain is subsiding, and the inflammation and repair phases of healing are achieved, then treatment goals can transition towards functional restoration. Thus in cases where there is trauma or severe acute pain, rehabilitation would not be a primary goal until the subacute or chronic phase. This is an excellent question and a corollary to the preceding paragraph. McKenzie in acute care is for severe pain with muscle splinting and antalgic posture.