A few years ago it struck the D.C. region's biggest medical insurer that the doctors who saw its members most often and knew them best got the smallest piece of the healthcare dollar. CareFirst BlueCross BlueShield spent billions on hospital procedures, drugs and specialty physicians to treat sick patients. Only one dollar in 20 went to the family-care doctors and other primary caregivers trained to keep people healthy. The company's move to shift that balance tells a lesser-known story of the Affordable Care Act and efforts to change the health system.