True, but I would doubt that you could come up with many a-political attributes to rate that would, as an aggregate, tell us if the person was a good president. I would assert that speaking ability, as you suggested earlier, has little to do with being a good president, except, perhaps, in times of peril. Indeed, in some respects, President Reagan’s general aura of “greatness” as President is a result of his ability as the “Great Communicator”. Those who look to see what his administrations actually did (his effectiveness as a President, if you will) might well want to bypass how he dressed things up (“Mr. Gorbachev, tear down this wall!”). After all, Bush the Younger was notoriously poor as a speaker, and that tends, I think, to cloud viewpoints of him as a President.
Then, there is the trouble of trying to find things that are truly “a-political” to rate. Some things seemingly not touched by politics would nevertheless be viewed differently by people of different political stripes (especially in today’s society, when bi-polarization of viewpoint is so strong). So I suspect that the attempt will fall on the rocks of actuality. 