Wenger fears his side's demolition "raises some questions" heading into the business end of the season.
"It was a very poor day. We were poor defensively, offensively," Wenger told BT Sport.
"Liverpool played very well, so congratulations to them. But it was a poor performance on a day when we couldn't afford it.
"Of course it raises some questions today because we were caught many times and were naive."
Asked how he would look to right the wrongs, Wenger added: "Defensively we need to be more stable. Today we were too open. From the front to the back we were not at the level we are used to."
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