I can't say if Chelsea has improved in their performance or not, it's when the new season starts is when we would know. However, their performance in CWC is impressive and their fate will be tested in the finals when they play against PSG who have destroyed and humiliated top big clubs in various leagues in recent times.
seeing chelsea's performance in the CWC has shown that their performance is quite improved, because to reach the CWC final is not an easy thing. but i agree that to see their real performance we need to wait to see how they perform consistently in heavier and longer competitions, such as the premier league, champions league, or even the fa cup.
as for the match against PSG, i'm not so sure that they can withstand PSG's attack. PSG is currently on fire and their mentality is very good. maybe chelsea's fate will also end up like real madrid yesterday, humiliated in an important match.