I tend to agree. Pep has made him the driving force of their attack, basically. He's definitely done a lot of work with him to give him that kind of responsibility this season. He wouldn't have gotten that anywhere else.
I'm also not sure he'd look quite as good and be as effective outside of City's current system. Their attacking play is designed for Sane and Sterling, currently.
I don't understand the argument.
Basically, every player needs a good team and environment to really perform. So what if Sané is flourishing specifically under Pep? He's 21 now, and he became a starter at Schalke at 19. It's not like this City is an easy environment to get a start. He's got huge competition, and he's made space for himself by performing. Who are we to say he wouldn't have done the same at Bayern? Let's not pretend our attack is deeper and denser in quality than City's.
Secondly, it's not like our football is so different from Pep's. Why would a player which fits with Pep's system not be able to fit with us? Our style didn't change substantially with Ancelotti, it merely got worse the more Ancelotti meddled with it. He merely let some parts of it fade away.
We played possession football involving high pressing before Pep, and we're still playing it after him. We have used wing play before him, still do it now.
Sané would have been perfect, and the signs are he might be growing into one of the best attacking players Germany ever had.