The Englishman now has a goal and four assists in six Premier League matches this season.
His dazzling display at the Etihad Stadium today earned him the Man of the Match award and Walker had nothing but praise for his compatriot after the victory.
"Phil [Foden] has been class," he said. I think whenever people write him off, he always comes back and proves them wrong.
"You have to understand he is still very young, he's still learning and he's still going to have a lot of fire in his belly to prove the manager wrong.
"As long as he keeps putting in performances like he has done since the start of the season then he can't be dropped, but I'm not the manager and I don't make the decisions.
"When they have a low block, you have to move them and find gaps. I've set it back to Phil and you need them goals to settle the nerves when it is going to be a difficult game.
"We showed grit and determination to get the points. The clean sheet is important. We have let a couple of sloppy goals in recently. But I think the lads dug in today and showed just how determined we are to achieve great things this year."
Rodrigo was shown a straight red card shortly after the half-time interval, after a coming together with Morgan Gibbs-White resulted in a dismissal for violent conduct.
Walker believes that going down to 10 men showed the adaptability of the players in the squad.
"It's not ideal going down to ten men," he declared. The manager made the changes and we have to adapt to that.
"It's something we have to do. It's about getting the three points and moving onto the next game.
"There's emotions running high in the game. He [Rodrigo] isn't one to start raising his hands so I was surprised to see the red card.
"I see it in a quick flash with no replays, so the referee has made his decision and we have to stand by it. As a person and a human, I don't think he has that in him."