A corporate turnaround is never easy. There will always be pain even as success remains a question. And a turnaround takes time. But only so much. And Marissa Mayer's time as Yahoo CEO seems to have run its course. The promises for a new future that she made back in 2012, when initially hired as chief executive, have come to naught. Activist shareholder Starboard Value is reportedly readying a proxy fight.

And yet, even Mayer has run out of reasonable time to make a difference, she's asking for more. "I would love to be running Yahoo," she told Charlie Rose in an interview. "We have a three-year plan."

A plan that sounds suspiciously like the others that went before.

This is a PR blitz, and Mayer wants to avoid being booted from the company so she can ... do something else, presumably. Just as Carol Bartz, a former Yahoo CEO, was pushed out the door. .

Not to say that Bartz or Mayer was inept. A turnaround situation is different from business as usual. There's a reason for the existence of turnaround specialists who can come in as a CEO, help fix a company, and then move on. It isn't a common skill, which is why there are specialists. They typically might get a couple of years to start showing progress. Mayer has been in place about double that and still says she needs more.

But it isn't clear that even a specialist could pull off a corporate repair. Yahoo is a collection of web properties without authentic cohesion. One of the criticisms of Bartz during her tenure is that she couldn't clearly answer the question of what Yahoo was. Any time you can't explain what your business does, you're in big trouble.

Mayer isn't any better in this regard. She's added properties (and spent a lot of money doing so). She's closed properties -- even more as of late -- and has opened new ones that haven't helped revive the company's fortunes.

It's less and less clear that the board and shareholders are willing to give her any more chances, especially as the company is already indicating that it will sell core assets. What will be left to run?

Ultimately, the lack of progress isn't the fault of a CEO when everyone taking that position does equally poorly. The problem is the company itself. Maybe it's time not only for the latest CEO to recognize the issue, but for the shareholders as well.