Chelsea needs a more agile midfield that can create passes and a more solid defense that can withstand attacks. Chelsea only needs a little polish on their attack, so the bigger focus is on their defense and midfield so that their attack can be sharper and better than last season. I still see Chelsea as a good team, even though in their first match of the season in the domestic league they suffered a goalless draw, despite having a few chances, which were wasted. Therefore, the Chelsea coach needs to evaluate this so they can truly be strong in this season's Champions League.
Chelsea have the history of winning the Champions League in the condition of the team not going well in the English League, but this season cannot be used as a reference that Chelsea can repeat the same thing. The midfield is indeed quite crucial because it is the brain of a series of attacks that are trying to be built and if the attack line is creative enough in building attacks it will be easier for strikers to score goals. Of course all crucial positions in football and I don't think Chelsea have not lacked good players, it's just that so far it has not been fully maximized in contributing to the team.