I would say one of the main weaknesses in Chelsea's squad is their defence. Although the performances of the attacking players have been erratic, Chelsea's attack cannot be considered weak. Sterling, Mudryk and Jackson are each quite talented. However, due to the poor bonding between the players, Chelsea players also missed many easy chances. On the other hand, the defence of this team is very weak. Conceded 41 goals in 25 matches. And the consistently poor performance of the defenders is why Chelsea are behind. Chelsea's defence needs to be strengthened. At the same time, the understanding between the players of the team should be improved by making changes in the match strategy. If not, we cannot expect consistent good performance from Chelsea.
It was a sad reality for Chelsea that night and even with all their attempt they never made any significant attempt that could have delivered them any goal in the match even though their ball position and chances were higher than that of Liverpool in the game, although just as you said, both the defence and attack was bad today because Liverpool squad put a lot of pressure on Chelsea's defence for long before eventually breaking through it to score that only game.
In general, one of the problems with Chelsea is the players, the club need to bring in a lot of new hands that can enhance their chances of performing better in the future, judging from Chelsea's predicament in the last few seasons, a lot needs to be fixed that could possibly position the club for a better outcome in the future.