I've already explained this. The Binder Twins, for which he is most famous for, is hardly a success story other than the fact the two survived the surgery. And while his "success" rate is supposedly normal for most neurosurgeons, I don't equate survival of surgery as a singular basis for success.
To elaborate, while he successfully prolonged their lives by years; one twin was comatose. Practically brain dead as a result of the surgery. He finally died about a decade ago. The other twin lives in assisted care, cannot walk, cannot feed himself among other things, and has never spoken a single word. Quantity of life is not the same as quality of life.