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.