The thing about Barry, in my City experience, is that he levels shit up. When he's injured, City tend to play a lot more risky. Attack, defend, attack, defend. With him on City keep a lot more possession, he's like a freakin' firewall. His passing is easy but he always help out the wingers. In defense mode, as I said, he's fantastic in support to a DM.
With just De Jong and Parker on, the team does a lot of fabolous tackling but the ball often tends to get back to the opposition. That happens much less often with the firewall active.