By time of day, I was referring to the imbibition of fluid by the disks. Also, MRI is only a static position, not a dynamic position, and cannot show movement pathology. I was not referring to RTC tears, only the spine. Perhaps time of day and position aren't that important, but my point is that MRI results have little correlation with pain.
As for most LBP resolving itself, the answer is still yes. The point is, tissues heal, yet you still have people complaining of chronic pain. In those cases I suspect psychosocial factors (fear avoidance, pain catastrophizing, etc.) I'm not saying the pain is in the patient's head, but in the brain. Is "PT" effective? PT is so broad so it's hard to say. What I will say is that exercise, especially aerobic exercise, is effective for preventing back pain, as well as a healthy lifestyle and relaxation. Nothing has changed.
I see you were a PT and now an attending physician. What made you transition? Have you had enough school?
Reference: Savage R, Whitehouse GH, Roberts N. The relationship between MRI appearance of the lumbar spine and LBP, age, and occupation of males. European Spine Journal. 1997; 6: 106-114.