Pep wants more control thats why Mahrez and Grealish play. Rico inverted means more possession and control in midfield. We are built in this system to control and supply Haaland.
Those tactics look to not work against teams that sit back and counter in Everton, Brentford, struggled with Fulham etc. But in a one off cup game
against teams that will come at us it could work wonders. I put in the Pep performance thread but thinking about it the tactics today would have been good against a team in the champions league that attacks. Like a Leipzig