It may or may not be the gauge that the general public uses, but, if a company can hold it's own on Wall Street it will last a lot longer then one that can't. You seem to be forgetting the most important part and that is public support. A good idea may have a value, but, it is meaningless unless the public holds that same view. However, without money to back it up while either building a demand or even maintaining, they will soon be on the bottom rung. The Disney Company is no longer a gamble, it is a sure thing.
As long as those two areas of examination stay high (stock value and demand) then Bob Iger will be an extremely successful business man. He won't go down in history as highly creative, which everyone seem to think is a necessity, but, he will be a huge success. I know that sounds like a bitter pill to take, but, there it is. Any high end executive, with minor exceptions, will surround himself with the kind of people that can be trusted to know what to do. It is foolish to think that one single person can have the ability to do everything themselves. They may take the credit for every good thing that happens, but, that is what they get paid for.
It is sort of like that silly question posted on another thread, Who really created Mickey Mouse, Walt or Ub. The answer is both, of course. Walt had the idea and Ub was able to make it be what Walt had envisioned. Walt, however, took all the credit, which is pretty much how it should be. Who takes all the credit for Apple? Steve Jobs didn't do the things necessary to create the computer, he told Woz what he wanted and it became reality. Comparatively how much credit did Steve Wozniak get publicly. Almost none!