The Mirror have been at this a long time before FSG showed up, though I wouldn't be surprised if there was some sponsored discrediting of Sterling performed on their behalf. The problem is, as it has always been, that Liverpool have a massively disproportionate presence in the media, because the combination of banal, hollow posturing and treacly sentiment you associate with tabloid journalism, is a particular brand of writing that ex-Liverpool players and LFC fans slide into with ease, moreso than the denizens of any other club.
Sterling has become a symbol now, and it's a symbol of something that they do not like. He represents the fact that they are not a big club anymore, not the all-conquering global brand that they've built themselves up to be. They're a selling club, like most of us. And if they can't hold on to a 20 year-old boy who's had one decent full season, even after throwing money at him, even after running one of the most intense media campaigns to discredit and intimidate him, then they will realize how far from the elite they have fallen.
If I were any of them, however, I'd console myself in the fact that it won't take long before the delusion takes hold again and they will thumping their chests with equal fervour next season, always next season, hailing some new great hope or other. Good luck, Jordan Ibe.