I'm sure that a lot of the people who rate Luiz so highly do so because of his 'filthy' bits of skill, but impressive as those moments are, they rarely/ever result in anything significant. He obviously has talent in some respects, but I don't think that his skill set translates particularly well to being a major influence on matches.
I think most people accept that he has limitations as a defensive player, but presumably many feel that his supposed 'playmaker' abilities compensate for this. But that really is the part that I have an issue with. I think the idea that he is a great passer is largely a myth. He is a sideways passer. He can hit long floaty diagonals when given time, but so can most players. He isn't an incisive passer, there is no penetration to his play. He doesn't have the vision of someone like McGinn. It is in games where we are in control, like the Brentford game, where this becomes more apparent.
Would it be different if he was played further forward? I'm not so sure.