Jordi Roura admitted that Barcelona do have a problem in defence, but Unai Emery was proud of his players despite losing.
A first half Alberto Botia goal gave the Rojiblancos the lead, but second half strikes from David Villa and Lionel Messi ensured that the Blaugrana claimed all three points.
But the Barca assistant has conceded that not keeping clean sheets could come back to haunt them when they face Real Madrid in the Copa del Rey next week.
“My intention for this team is always to keep a clean sheet,” he told a Press conference. “And it is true that we are having problems in this regard.
The mistakes we made were avoidable and we have to improve.
“We may be the highest scoring team, but at the back, positionally, we have to get better.
“It's especially relevant considering the Clasicos coming up. They are always important games, but Tuesday is a decider for a competition we want to win.”
The 41-year-old meanwhile, has insisted that he was happy with the performance, even after slipping into the bottom half of the table.
“I am satisfied,” he told a Press conference. “A defeat always leaves a bad taste, but we have to look at the positives.
“We have taken an important step in building something that will help us in the future.
“We had opportunities to tie the game, but we just couldn't do the little things well enough.”