No. Of course they do not only have problems with the defensive. But what I meant is that we can not take the departure from Lewandowski as the reason for lost games. Of course goals have to be scored. But if the defence has problems it is easier for the opponent to block the offensive and overcome the defence. It would be strange to always win with 4:3, 5:4 and so on. 
Yes, that's what we saw today, they have gaps that the opponent can use to score goals. It's true that they can win games by scoring a lot of goals, but they also concede a lot of goals, that's a problem. Because they will not score many goals in every game, because luck must also be considered.Now they have two problems, namely defense and goal productivity. Even though they scored a lot of goals early in the league, it was not enough as they needed goals to win every game.