Honestly pre-season matches shouldn't be the yardstick to determine the formidability of Chelsea in the upcoming season, recall that in most of the pre-season matches many Chelsea substitutes were tested or played in which when the league matches starts properly only the main squad selected by Pochettino will enjoy a regular playing time and majority of Chelsea first team squad are new signings thus it might take the team some period of time before they will adapt to the league consequently the team might have some mix results some wins, draws and some losses thus Pochettino should be given enough time and Chelsea fans should also exercise patience before the team will begin to be stronger.
Even though the results of the pre-season matches are not 100% a benchmark for the quality of the team, at least the coach can take it as proof that the new system is starting to be useful for the team. Chelsea have tended to decline in the last few seasons, so it's only natural that they start trying to get a new rhythm of play that maybe they have adopted since pre-season. Chelsea have started to improve, it is proof that Pochettino has a system that is useful in building the quality of Chelsea's game next season.
I can consider that Chelsea will change next season with Pochettino, that's because he is one of the coaches who understands the technicality of the game even though his title record is not as perfect as other teams. I like Pochettino's style of play and the way he adapts strategy, but it's a shame he hasn't been able to win many titles with the team he has coached so far.