Stoke fell 1-0 at home to Norwich City on Sunday.
Walters said: "Thinking of ourselves as favourites could have been the problem.
"The bigger games take care of themselves, against Man City and Arsenal, but Norwich was a very important match and we had to compete.
"They had a plan and stuck to it, so we had to compete, match them and work the space to pass.
"We can't just turn up and think we are going to play like we have in other games. You have to earn that right and we didn't."
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