But Walker says a high team spirit will spark a revival for Pep Guardiola's side.
"I have just said in there: 'I look at you guys, you are my family'," Walker said. "I see the lads on the bus more than I see my own kids.
"We are going to experience ups and downs throughout our playing careers together at Manchester City. Fortunately up to now it has been plain sailing. We have gone on and done what we have done.
"We are only human. We don't go on to the pitch expecting to draw or lose but there are going to be mistakes in games. Some things will cost you games.
"But now I feel we have got to pull together as a squad and get the belief going again and make sure we do go on a run to put some pressure on the people above us."