And although Wagner has defended his stance on this perceived second-string line-up, Blues boss Redknapp has also jumped to the German's defence.
"It is Huddersfield's business what they do,” Harry Redknapp said. "They have got to the Play-Offs and it is not their fault other teams are in a relegation battle.
“Why should they take care of us or Blackburn Rovers, Nottingham Forest or anyone else?
"Their manager's job is to get his players right for the play-offs. He cannot be worrying about other teams.
“I did exactly the same thing when I was QPR for the last two games."
The victory was Harry Redknapp's first as Birmingham City boss after taking over a fortnight ago from Gianfranco Zola and only a third in 24 league games for the side.
It leaves the Blues two points clear of Blackburn and Nottingham Forest but with an inferior goal difference, and Redknapp said: "We need to win in our last game at Bristol City to avoid relegation.
"We have a two-point advantage so a point will make no difference. We simply need three points but it all depends upon the results of the other clubs."