I always like the most qualified candidate arguments..... It is hard to determine qualifications.
It probably wouldn't be hard to reel off half a dozen major qualifications for being a GM. A GM needs good public relations skills; a grasp of analytics; an ability to be decisive; strong negotiating skills; strong organizational/people skills. There, that's 6 right there and I'm sure another 6 are low-hanging fruit as well, plus another dozen or two of lesser importance.
And it's not as if stellar abilities in one area will necessarily hide deficiencies in another - each of these categories is a potential career-killer. OTOH, it would be a rare candidate who didn't have a deficiency or two that will need to be managed. Two great candidates could have very different profiles.
So, even if we could determine qualifications from our outsider vantage points, the bottom line is that "most qualified candidate" is way more linear and analytic than even this linear-and-analytic writer is willing to be limited to. There can be more than one right answer to the question of whom to hire.
Was Ng the most qualified candidate, or even the right choice? The question is for me a giant red herring, relative to the post that kicked off this thread. Congratulations and good luck to the new hire, that's the farthest down this tangent I would want to go.