The thing about Forstall's achievements is he did them all under the shadow of Steve Jobs.

Is it that he had to take a more active role now, and not just be a Jobs man?

Is it that Jobs could bring talented people together and keep them there and Tim Cook is failing to do that?

I'm almost certain it's neither of those, but they serve to illustrate the point: when people think of iOS, Scott Forstall is not even close to the first person they think of giving credit to.