I agree - but there's two sides to this story I think. Marv yes, but I think Luiz is a lot better at it.
He shows for the ball, receives it and looks then to distribute. When we play 5 at the back, there is such a gulf between defence and attack that he can only really pass to Jack or go backwards - when Jack is marked it's pretty difficult for him.
If we're to play 5 at the back and retain the ball, the wing backs need to show for it a lot more, one of the wingers need to drop back slightly and Marv needs to improve. We're moving in the right direction with it, but a few tweeks are needed in midfield so we don't just keep inviting pressure.
Prime example was when he got caught with the ball for their goal, he doesn't want to keep passing backwards, but nobody is showing for the ball.