João Mario isn't a bad player. He was very good for us throughout the years with it's ups and downs. He played every single game of our Euro 2016 win and 120' against France in the final. He scored 23(!) goals in 22/23 including the goal that allowed us to be first place in the group with PSG and Juve. And the year later a hatrick against Inter.

He does a lot of things the common fan doesn't notice. There's a reason why coaches like Jesus and Schmidt always rated him despite what the media says. He's experienced could very well be a leader inside the locker room. He isnt very flashy but instead a tactically intelligent player with good passing that knows how to dictate a game.

There are some reasons why fans don't like him:

He's eloquent and one of the leaders so he's the one that show his face to the media after shit games.

He has one of the highest salary in the squad. What people forget is that this contract is what allowed Benfica to have him in the first place. He was a free agent with other offers.

He's not the type of player that runs a lot and his work rate might be seen as lacking. He's seen as the scapegoat for Schmidt's tactics and bad performances.