Yea, City defense is weak and they need to strengthen it, if they want to improve their performance to the best. The players are old and getting weak which is affecting their performance. It's very disheartening that City is be 20 points away from the top of the table. I hope that City will be able to finish on top four this season in order for them to qualify for UCL next season.
Even before now the brilliant attack and forward possessed by City has always been a shield for the defense making them appear really effective because they usually make up for their lapses by scoring multiple goals which gets them to to concede little to almost no goals at some point but since their attack and forwards began to suffer some set backs they have literally made it obvious how weak the defence can be and that has been seen in their recent games.