This is it for me. If you look at his stats against the best players in the world when they were 20, he's generally better, Messi aside. In this 'poor season' he's just had, he created over 70 chances, unfortunately for Borini, Lambert and Mario. Whilst he'll have to defer to Silva a bit, imagine creating that many chances for Aguero - you'd be looking at 20-30 assists and his movement would have meant you could create even more.
Over the last two seasons, his pace has terrified us. Whilst Navas has it he rarely uses it, so although we'll lose some of the defensive work, there's no way anyone will play a high line against us. And his speed in and around the box will create chances, free kicks and penalties when he's linking with Silva, Aguero, Nasri, KDB etc