1. To beat City you need very fast players on the break, for example, Muani for Vlahovic, Weah for Kostic, Mbangula for Nico. Instead of looking for a quick buck by selling the players that actually try to play and were useful, sell the expensive flops now. Luiz and Koopmeiners are trash and Vlahovic can move on. That will be plenty to rebuild with.
2. Why play 3 at the back when they always have fast wingers? Adding extra defensive mids doesn't solve the wing problem and Kelly was completely lost with nobody covering him either. Why not change formation? 3-4-3 requires possession and a attack mindset so that the back 3 stay up a lot, a defensive 3-4-3 gives you zero outlet to release City's pressure so conceding 5 was expected.
3. Attack is the best form of defence in modern football, those days of parking the bus are long gone. Pep has got his new players and a bunch of bench warmers playing slick football, while we only focus on "pressing" in training. Why not cultivate a new style and thinking? Mbangula would've been way more useful than Nico or Vlahovic. Is Tudor another dictator coach?