The Basque trainer was philosophical after his team's mauling at Camp Nou, claiming his players were already looking ahead to the next game as they went in 5-0 down at half-time.
Barca had been pegged back to 2-2 in consecutive matches - at Real Sociedad and then at home to AC Milan - in a disappointing week, but turned on the style to thrash Osasuna on Saturday.
Lionel Messi scored a hat-trick, David Villa bagged a brace and Xavi and Cesc Fabregas were also on target in a sensational display from the reigning champion.
"If you try and defend, and sit back, they beat you, either by four, five, six or eight," Mendilibar said at the post-match press conference. "They were angry because of their so-called 'mini-crisis' and we paid the price for that."
The coach revealed his players were frustrated after the match, but claimed they had already been looking ahead to their next game by half-time, when they went in 5-0 down.
"The players are down, but they will get on with it. When you come in 5-0 down at half-time, you are already thinking of the next match."
Despite the heavy defeat, Osasuna remains in the top half, having picked up a win and a draw in its opening two league games.