Barca thumped Betis 5-2 at the Nou Camp.
Former Barca defender Bartra stated: "We have faced a Barca that was under pressure after a loss and that has made us drown. We leave with a lot of anger because we got ahead, but then they passed over us like a steamroller.
"Everyone was very good under pressure. We had less of the ball than we wanted. They are a good team. Last year it could be, but this one was not. Now we have to turn the page and learn from mistakes."