Like I said, if Barca can be 2-0 up before HT, anything could happen. It already happened in the past against AC Milan, 4 goals in return leg without conceiding, so there's still at least 20% chance.
They are playing well and they are second now, I watched all their games. The losses are mainly due to some poor individual errors, not tactical errors. Also, they created so many chances per game, but they do lack the finishing. G.Jesus could have changed that but he is out for the next few months.