He might also know that he's not a great goal scorer and feel that once Aguero leaves, that's something we will desperately need - more than occupying 2 defenders, holding the ball up, linking play, creating space for people like Sterling to run into.
And he definitely knows, having seen Sterling over the past 3 years that your finishing ability is not set in stone when you're 22. He's got plenty of time and plenty of games to work on his finishing and bring it up to the level of the rest of his game.