The blame should be directed to all of their defenders and Maresca. I try to point out some key points here.
Sounds interesting, i think, it's weird to see Chelsea and their position right now, 2 win, 2 lose, 2 draw, and 2 red card, this is really not a good start for them. However, if the loss 1 player became the reason, then the manager must immediately take a decission to set an alternative strategy when they are playing with 10 men because of red cards. If they continue with this strategy, it will be easy for their opponents to beat them. On matchday 7, they face Liverpool, which will be even more difficult for Chelsea to get 3 points. Full preparations and training needed for chelsea.
We cannot consider Chelsea as a strong or weak team because they are currently playing at a poor performance, but in the next match, either they will become strong or they will appear weak. If Chelsea works hard and improves their record, they will also do quite well in the league and the bad predictions they are making will also improve. They should definitely improve and if they do not do so, they will only harm their own team, which will make them face weakness going forward. This is the reason why Chelsea will go down further and this match seems difficult to win in their favor because Liverpool is a good and strong team and they play better than Chelsea, which can cause a lot of pressure in the match.