Rampant speculation suggested that Scott Forstall and John Browett were fired from Apple due to their inability to play nice with others. Apple never officially announced a reason for their departure, but Cook says that happy collaboration is a key ingredient to the company's success.

From Businessweek: "The key in the change that you’re referencing is my deep belief that collaboration is essential for innovation—and I didn’t just start believing that. I’ve always believed that. It’s always been a core belief at Apple. Steve very deeply believed this…

"So the changes—it’s not a matter of going from no collaboration to collaboration. We have an enormous level of collaboration in Apple, but it’s a matter of taking it to another level… So how do we keep doing that and keep taking it to an even higher level? You have to be an A-plus at collaboration. And so the changes that we made get us to a whole new level of collaboration."