"Listen, people can talk. I've seen a few things or my mates have text me about tactics, personnel, this, that and the other," Walker told The Daily Mail.
"It's a game of football, it's 95 minutes and anything can happen. Obviously, we wanted the result to go our way but the manager, or whoever, he picks who he feels can go and get the result and what's best for the club.
"When he gets it right nobody says anything and when he gets it wrong – or when they think he's got it wrong – people are questioning things."
Walker went on to admit that the City players could feel the game slipping away from them as the Blues successfully executed Thomas Tuchel's high-pressing game plan.
"I think it's a little bit unfair sometimes when as soon as Manchester City don't win then it's tactics or maybe players on the pitch, but we needed to do more and it's as simple as that," he added.
"I don't think we created enough in the game and I don't think I'm speaking out of turn by saying that, I think everyone could tell on the pitch."