Luiz is fine in the right system and with the right mix of players around him. We don't have either, but equally we don't have enough centre-backs who can pass at the required level for Arteta's plans. If Chambers was fit, Holding fully recovered and Mari hadn't got crocked, we wouldn't need Luiz. But without him, we're one more knock from a parthership of Holding and Zech Medley for the rest of the season. I don't have a problem with Luiz for one more year, but he's here for bigger picture reasons than his own ability. Were Saliba a year further on, Luiz would be gone.