Joaquin Caparros admitted his side were poor, as Gerard Pique conceded that Barcelona dominated the game.
The Bermellones let in three goals in the first 45 minutes, before rallying back in the second period.
But the 57-year-old has lamented the unnecessary head start his side gave Tito Vilanova's men.
“We were really poor in the first half,” he told a Press conference. “We had no confidence on the ball, and lost possession an awful lot.
“In the second half we had to start all over again. After the break we had a lot more confidence and passed like a team.”
The 25-year-old centre-back meanwhile, made a winning return to the Blaugrana starting XI after a number of weeks out through injury, and has conceded that was pleased to get back to the action against Los Bermellones.
“I felt really good,” he told reporters after the game. “If you don't play for a long time then you always have some doubts about your fitness.
“But I felt very good and am delighted to win.
“We had a difficult period in the second half, but overall we controlled the match.”