#4 Defensive weaknesses

Barcelona looks shaky in the defense this season as they have conceded 20 goals in LaLiga in 18 games whereas they conceded just 29 goals in the entire league season last time.
The Catalan club signed French center-back Clement Lenglet this season to further strengthen their back four, however, the defensive line has looked ineffective in keeping the opposition out as Barca's German goalkeeper Marc-Andre ter Stegen has managed to keep only 6 clean sheets in 18 league games.
Barcelona also conceded four goals at home this season for the first time since April 2003 when they were beaten by a scoreline of 4-3 against Real Betis.
Samuel Umtiti's hamstring injury in November also added to Barcelona's defensive woes as the 25-year-old center-back still does not have a confirmed return date; however, Valverde in a recent interview claimed that Umtiti is close to making a return to the Barcelona camp.
Barcelona's defense has also been exposed in the Champions league as they conceded 5 goals in 6 games and were able to keep only 2 clean sheets.
Blaugrana will have to sort out their defensive weaknesses in time or they would be prone to yet another early exit from the Champions League knockout stages.