"There was plenty of evidence of lazy defending," said the former Liverpool and England defender on Sky Sports' Monday Night Football Show.
"Lazy defending for me means 'won't run'. I saw signs on the weekend of something worse - 'can't run', which could be a bigger problem for City going forward.
"We talk about lazy defending and I tell you what I mean by that. Sagna should be turning around and being on his toes [for Arnautovic's first goal] so he can see the ball and his man. You have to be able to see your man as a defender. When I talk about lazy defending, I mean not getting in position early and then walking.
"But the bigger worry is can't run - Sagna has three or four yards on Arnautovic, but who gets there first? Sagna is looking over his shoulder and does not know where he is, but he still gets there first.
"The reason I am talking about Sagna is that he is now 32, almost 33, and has played 26 games this season for club and country and it looks like it is too much for him.
"But his body position is wrong [for Arnautovic's second goal]. He has to be facing the player and also as a defender you have to be inside the attacker, but Arnautovic is inside him and he has to be back round and that is the lazy bit there.
"And if he gets in position early, the goal does not happen. Then he is walking, walking and suddenly Arnautovic is gone and he can't run."