This isn't actually true. They really struggled when opponents managed to play at high intensity and press them high well. Teams back then just didn't have either the stamina or tactical sophistication to pull it off in more than short bursts. Mourinho's fine tuned anti-barcelona strategy was just that: high intensity high press bursts followed by periods of rest in a low block. And Barcelona seriously struggled to deal with our press in those periods. Liverpool and city do that normally and face teams that are also much better at it
Disagree totally, and the Mourinho thing is the worst example. Take the Inter victory in the Champions League. Inter hardly had the ball and were content that way. It was all Barca in possession, there was no mix of high press and low block, it was all low block and counter.
Barca were the team that used to do the energetic high press and once they won the ball back you never saw it again. The key thing about that Barca team was that every player was comfortable on the ball and the midfield especially so. I think they were definitely a better team than current City.