Long way to go but it looks like Haaland has caused a regression whereby they rely on him to score and the team has suffered as a result. Pep will most likely adjust for the 2nd half of the season though and go on a run.
They look like a team in regression, not because of Haaland, but because they are getting older, and currently struggling to play 3 competitive games in a week without picking up injuries to key players, and the squad players coming in are not quite at the same standard to keep it all ticking over. De Bruyne doesn't get a rest because they need his creativity, and tonight he was chasing shadows and looking old and fat.
They will be back to a normal formation on Saturday, but I can see Rashford getting at that back 4. Ake made Walker Peters look like Ronaldinho tonight. Stick Casemiro on De Bruyne, Shaw on Mahrez, Dalot on Foden and cut off the supply to Haaland. He can't do it on his own.