He's played for some of the biggest teams in the world (Inter, Juve, City, Bayern) and under a number of different coaches such as Spalleti, Allegri, Pep, and Tuchel. Which is quite impressive as all four of them have their own way of doing things.
But it seems like despite his incredible talents he has the knack of falling out with basically every manager he's played under which was evident when he was at Valencia as well. He gets dropped due to tactical reasons he cannot handle it like at all.
He would no doubt be an obvious improvement for our RB spot but if the likes of even Pep and Tuchel didn't want to deal with his stinky ass I'm not sure how Xavi is going to handle him at his worst.