While I disagree with your wording, I do think your assertion that USC should have had as an AD prerequisite someone who had been an athletics director at another institution is a valid one. At least that's above board and not an outright lie regarding RT using "leverage" to get the position, which others have posted.
In other words, while I don't necessarily agree or disagree with your opinion, I do respect it. 👍
However, I also disagree with your "baseball coach as AD" analogy. You could make a "football coach as AD" analogy or a "basketball coach as AD" analogy, and it would be just as (il)legitimate.
Truthfully, I was a bit surprised when I heard the announcement that RT had been named AD, as I figured the school would have hired someone who had served as AD elsewhere, and Ray would accept an AD position at a small school in the region, and then become USC AD when Hyman's replacement left.
I'm not very well versed on all the duties of an AD, but I do know that it does not begin and end with how well the football team does.