I'm an actuary for BCBS and do oversee the provider reimbursement methodologies for providers. It's a lot more involved than this, and there is a huge difference in reimbursement methodologies between hospitals (institutional) and doctors offices (professionals).
We work off of charge masters that hospitals and doctors offices send for their pricing. We actually have pricing factors and matrices for each billable diagnosis code. We even have it broken out by area factors. For example, you could see the same doctor for the same procedure in an urban area and a rural areas and the insurance will pay different prices depending on where you are. Doctors and hospitals in large urban areas get reimbursed less than doctors and hospitals in rural areas or less densely populated areas. It's all a numbers game.