City were hammered 4-0 at the Etihad - marking their fifth consecutive defeat.
Richards said on Sky Sports: "I am flabbergasted.
"Spurs were excellent. (James) Maddison was the best player on the pitch.
"From Man City's point of view it is truly awful and I don't say that a lot about City. They were off it, the distances weren't correct, they were dominated in midfield, they have a lack of energy, conviction, they didn't know how to break Spurs down.
"I thought the contract (signed by manager Pep Guardiola) would give them a lift but it wasn't meant to be.
"It could have been a blip but it was more than that looking at that today. To be at the Etihad and not score in games like this, it's a bad one."
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