Earlier quoted context omitted.
I gather you are not a healthcare professional, hence the artificial dichotomy stemming from your perception as an outsider. Medical competency is very difficult to assess objectively. You're good/bad because people say so. There isn't any form of performance feedback.
How can that be? A patient gets diagnosed. There's treatment. There's an outcome. That can't be measured? And assessed? There's data flowing all over the place. But perhaps the lawyers and the insurance stand in the way of improvement?
GP: This condition X is much worse than normal, so I'm going to refer you to Dr. A, the best I know in the field.
Aggregate enough of this and Dr. A has worse outcomes on paper for condition X than everybody else, since s/he gets the patients with the hardest to treat coming in.