Barcelona got another win which is against Alaves this time. The final score was also quite decent to improve the morale of the players. But the weakness in defense is still clearly seen. 
I don't feel like it will ever get better than this during the rest of the season either. As long as it is enough to keep them in top four it would still be some consolation for Barcelona. I'm mentioning this because Athletic Bilbao aren't far away from top four now. It would be like a nightmare for Barcelona if they don't even manage to join the Champions League. I hope things don't come to that point.
It seems that this is according to predictions and actually Barcelona is much better away than at home because the three defeats occurred at Camp Nou so when they faced Alaves and managed to win it was not that surprising, but what you said is true is that their defense has not improved and they always concede goals in every match.I don't feel like it will ever get better than this during the rest of the season either. As long as it is enough to keep them in top four it would still be some consolation for Barcelona. I'm mentioning this because Athletic Bilbao aren't far away from top four now. It would be like a nightmare for Barcelona if they don't even manage to join the Champions League. I hope things don't come to that point.
Barcelona will certainly be more worried about not being in the top four at the end of the season than defending the championship which seems to be closed, even though in fact if they can return to playing in the Champions League their performance will be average because next season probably won't be much different because the finances haven't improved and it's certain that Xavi Hernandez will leave the club but economically it will help the club because they get more money in the Champions League than in the European League.