Really? I think the way Sané is attacking, moving with pace behind the defence line with and without the ball and his shot efficiency is quite different from Raheem. That's just an honest view of Sané's ability. Nothing to do with Raz.
Why should that affect Sterling in any way? Or even denigrate. I can't see that.
Sterling has to improve a lot of aspects in his game. Technical ability, confidence, end product have to get better. For example the way Robben and Costa are cutting inside and score is a nice option to have.
That said Sterling is very important for City, he is working his ass off and he makes loads of assists. Still he has to improve a lot.
In hindsight I should've added the bit about social media to that quote. The usual thing you read on Twitter and the likes is that Sané is so much better than Sterling, there's no need to do Raheem down just to make the point that Sané is good.