You think that it is a false confidence booster, as long as it boosts Chelsea's confidence, it is effectively a confidence booster. They might play against my local sunday league team and win 3-0. If that is a confidence booster for Chelsea, it works. Who are we to say that it is a "false" confidence booster. Confidence is something very volatile and subjective.
NSJ is not a poor team. They won their countries title, then you are never a poor team. NSJ is one of those teams that plays CL unexpectedly (from their own point of view). For most overachievers this is the beginning of the end because they overinvest on mediocre players with high wages. NSJ did not do that. Hats off to them.