Chelsea should be underrated completely in the Champions League. They have no track record, just that once they won the CL against Guardiola doesn't mean they are not experts in the Champions League. Chelsea is not a contender and their is no hope for them. They didn't take Champions League seriously than English Premier league, what happened is that EPL was stronger and hotter for them. Everyone wants to do well in EPL at the same time this season. There is no great hope for Chelsea in the CL.
In fact, the opposite is true. Chelsea have no hopes in the Premier League as they have already lost almost as many points as a champion can afford to lose points in a whole season and in the Champions League they are on equal footing. Therefore, it would be logical to try to get into the top 4 in the Premier League, and to perform as well as possible in the Champions League. Such a task looks more realistic than trying your best in the Premier League with so many lost points.
Change of the coach is surely having big blunder by the new management of Chelsea which is not going down in Premier League and Champions League spot for the last four is also not favourable for them because suddenly things going down badly, and they have no suitable strategy which helps them for having better result and improvement in performance as in start there were rumours Graham Potter could be on driving seat and things could be not difficult for them in coming season for having good result and better spot but nothing positive happening with most chances we will be able to watch them with poor end of this season and new dilemma which is surely not good for the management.