He's a terrible LB. That isn't general consensus because he's a scapegoat. A perfect example of scapegoating would be people getting mad at the keeper when Mats conceded a corner at his near post because Malboro decided to duck when the ball was coming to him. His performances at CB far outshine his performances at LB and I don't think there's a single time where he had a standout performance at LB despite constantly being used there. I don't even have to ignore everything positive he does because he does very little to be proud of him for (When playing LB).
Nah, it was pretty divided between Ter Stegen and Marlboro & Suárez about whose fault it was for allowing Papadopoulos to score. There's a much better example of what scapegoating actually is, I recommend you to go back and read the comments on this thread right after our draw against Deportivo. If someone didn't watched the game and based his/her opinion on Marlboro's performance from what the majoirty have said, he/she could believe that Marlboro was single handedly responsable for it. But as I said earlier, it's not true and I already explained why in one of my previous posts. As for the last sentence in your post, you literary did that regarding Marlboro's performance against Real Betis. He usually play as LB only if Alba needs to rest, don't really understand why're saying Marlboro is constantly used there.