It's true that Barcelona has a poor defense, which could have been the reason Barcelona couldn't beat Rayo in that match. Now, Real Madrid is certainly very happy to see Barcelona only get one point, and of course, Real Madrid sees this as a boost to their hopes of winning trophies this season, as their toughest rival has seen a decline in performance.
I actually can't agree with you at all. Maybe Barcelona's defense is weak, but you can't blame Barcelona's defenders for losing points against Rayo. I also saw it was a nice corner kick & Fran Perez was able to give a nice finish, I also expected a better performance from Barcelona's attack. i've seen Barcelona was even able to create several chances, but in the end they failed to score. so i wanna say Hansi Flick now has to identify the weaknesses of the squad and Barcelona will become stronger even with Lewandowski back in the starting XI.