Joanthan de Guzman netted twice for Swansea as they recorded a 3-1 victory, and Pulis revealed that he found it hard to describe why his team had performed so poorly.
"We had a bad day at the office - we weren't right from the start," Pulis told BBC Sport. "You get these days during the season when, for whatever reason, it doesn't go your way. That was one of those days."
However, the Potters manager refused to steal credit from Swansea, who are now ninth in the Premier League.
"But I don't want to take anything away from Swansea - they were fantastic," he added.
Stoke have only won once in their last six games.