@Luke, how is your thyroid function?
This is probably an overly simplistic explanation, but my mechanistic guess is that progesterone is anabolic, supporting the thyroid/parathyroid glands, the main glands responsible for the integrity of all connective tissues in the body, and lowering the catabolic hormones cortisol, adrenaline etc. The plumber’s thyroid may have been healthy enough for Progest-E to reverse the damage. For someone like myself who was chronically hypothyroid, Progest-E provided only temporary relief.