He played something in between, Marseille were pretty fluent between 3-5-2 to 4-4-2 in the game.
Don't think it's fair to say he was weak defensively anyway, he's very inexperienced and last season got six starts early in the season then another six in the end and in most he did well defensively, no worse than Tierney in my view.
He's an undisputed starter in Marseille and it shows, he's playing with a lot of confidence both going forward and defensively, tries a bit too much still but definitely worth keeping tabs on. Wouldn't be the ideal solution but I'd be happy with him taking LB next season and moving Zinchenko centrally.