From the 3 seasons that I tried to show in the picture, Barcelona managed to score more than 80 goals every season even though they didn't win the title. At that time they still had Lionel Messi and Suarez. But this season they have only managed to score 32 goals in 21 match, it is a result that is not imagined by everyone about Barcelona.
Previously, Barcelona has some great strikers who are always consistent to score almost every match. Not only Messi and Suarez, but they also have Griezmann and Dembele who still played quite well at that time. These strikers were supported by good midfielders such as Rakitic and Vidal. Now, those players have moved to other teams and Barcelona cannot find the best players to replace their roles. Considering this matter, I am not surprised to see a lack of goals made by Barcelona nowadays. I even predict that they are difficult to score more than 60 goals at the end of this season.
I think the problem why never have success forward on Barcelona right now because depending with midfielder position, last several season Barcelona have great midfielder like Iniesta, Xavi, Raktic and Vidal looks easy for forward how to make many goal each season. But now almost forward looks not easy how to scoring on every match and depend with Barcelona goal in this season where each match just score one or two goal only. Need looking for new midfielder position because with De Jong only is not enough how to give assist for forward.