When you don't like someone (or something), you find any way you can to attack it. When he was scoring goals he was criticised because he was offside once. Then it was that he didn't make his own goals out of nothing. Then it was that he never scored important goals. Then it was because he never scored against good teams. Then it was because he was always in the box. Now it's that he's never in the box.
As with every other player/personnel at City, eventually it all ends with, "I was wrong to criticise player X", as we've seen currently with Stones, Pep, and Gundogan, as we've seen with other players in the past, and as we'll see with other players in the future.