I don't think that Chelsea is currently one of the best team in EPL because the last time they lifted up the title was eight years ago. How are they one of the best when they haven't proved it. Winning CWC doesn't mean that Chelsea has picked form to the highest level. The season just started, let's see how consistent they will be in their matches.
Speaking of results, maybe we can say Chelsea is a little better than before even though the achievement did not fully place them on the list of one of the teams that were able to compete for the title. Waiting for some matches in the Premier League becomes a picture of how their strength this season and if they are able to perform consistently and compete in the top three standings will open the way for Chelsea to compete.
Arsenal and Liverpool are still strong enough so far and Tottenham is surprisingly able to defeat Man City, but this is not the end because the league has just started and some teams still have difficulty in achieving a much better form of performance. Winning the Club World Cup does not guarantee Chelsea can be much stronger but they get better.