I did cover why it worked in Juventus and France
Pogba never took the initiative and never tried to work as a team player. Every team has only one solution to fit in Pogba, a formation where Pogba has two midfielders protecting his back, in France, it was Matuidi and Kante, now Rabiot and Kante. In Juventus, two of the trio Pirlo, Marchisio, and Vidal. Either that or you won't be getting more than 7 out of 10 from him.
Being a world class player requires more than 10 - 20 at best - good games for a club in 6 years.
Of course, which is why I think leaving may the best option for both parties.