Although Chelsea performed quite well in the Champions League, it did not guarantee that they did the same in the English League. As many as 14 matches remain and if we look at Chelsea's schedule in the English League, opponents are more focused on the English League. So I'm still not sure Chelsea will focus on playing safe in the Premier League after what Chelsea got the results do not guarantee to meet the requirements for the top 4 rankings. Therefore, for this season the opportunity that Chelsea can only use is in the Champions League. Actually it won't touch the semifinals.
When faced with a stronger club, Chelsea will do more than that but when facing a weaker club, Chelsea seems to lose strategy.
While playing a mid tier team, top teams tend underestimate the team and the weak teams approach the game with a mind of undoing the top teams while, when they play against the top teams, it becomes a challenge and some means to test there form. Its just something normal.
Good enough for Chelsea, they've managed to record two wins, one in the EPL and the other in the UCl. They might manage to pick up the pace from there. The goal for Chelsea now is no longer about contesting for the league trophy but, to regain there spot in the league as an elite team and that means, they've got to fight for the top 5 at least, to make it into the Europa because, a UCL qualification is very unlikely.