Marissa Mayer knew what she was getting into. She’s getting big bucks to turn around the once-mighty Yahoo!

From my standpoint, the company’s problem is very simple.

Yahoo! has not embraced platform thinking. Unlike Amazon, Apple, Facebook, Twitter, Google, and scores of others, Yahoo! doesn’t really encourage external innovation. (Yahoo! Pipes showed enormous promise but, for whatever reason, went nowhere.) Until the company does, I’m betting against a turnaround. In other words, the problem isn’t inside Yahoo! It’s outside–and no internal policy shift can change that.

As I write in the book, building a platform isn’t easy, nor are results guaranteed. Success in this new age hinges not upon people being in the office. It’s about what happens outside of the office.

Big difference.