City have enjoyed a degree of success in the five-and-a-half years since owner Sheikh Mansour took control at Eastlands, with former manager Roberto Mancini leading the club to FA Cup and Premier League glory in separate seasons.
Despite experiencing a fruitful period domestically, the Sky Blues failed to make their mark on the Champions League and, considering the level of investment into the playing staff, Mourinho believes that the Sky Blues have underachieved overall.
Speaking to reporters ahead of Monday's showdown at the Etihad Stadium, the Portuguese said: "They won one title, won a couple of cups. Only in Europe they didn't do well, or close to doing well.
"Speaking objectively, they did very bad in the Champions League in previous seasons, also in the Europa League.
"But the team is fantastic, the squad is fantastic and normally they (should) win more titles."