He knows Sports from a wide perspective. He does not know the sport as an authority but does know the kinds of questions to ask to get skating experts to talk about the sport in an authoritatve and interesting manner.
He does NOT present himself as a skating authority, and that is much more honest than what many other sports hosts project to the viewer.
I find him to be one of the few consumate professionals in broadcasting in presenting sports on TV as Sport!
A TV-personality with a personality? It's a plus, I agree. So is it right to assume that Costas' writers are not on strike?