Going by the Chelsea history, whenever Chelsea reaches a major final, they never underestimate their opponents and always strive to provide a great performance. I thought it would be an equal-chance game, and even if Paris Saint-Germain wins Chelsea, Chelsea would make it difficult for them, but Chelsea ends up controlling every position, particularly in the first half, and playing aggressive defense in the second half. If we look at Chelsea's performance this season, we can see that they are the weaker team against Paris Saint-Germain since, even in the English Premier League, Chelsea starts the season poorly and hardly made it to the top four.
They are a weaker team than PSG but in a final match, a weaker team can beat a stronger team as history shows many times. Chelsea knew it and tried hard to beat PSG, and eventuallly they succeeded to beat a very strong opponent at the moment. With this convincing win against PSG, Chelsea did not win a final match, got a trophy but they actually harvested more things than that. It is one of preparations for a new season that is promisingly better than two latest seasons for Chelsea.
Maintain the energy from the beginning of the game till the last half of the game was the advantage Chelsea had over PSG. I never expected this kind of performance from Chelsea and it really got me surprised the almighty PSG lost without having a chance to get a single goal in a final that the hae worked so hard to get to. Surprises like this actually does make the game more fun and interesting, since it was a final I would have loved to see teh game get to extra time so I just get they feel of a finals where the tension gets high up there and the suspension becomes intense and a the end we finally get a winner.
This is not luckiness but an effort of Chelsea to score goals, maintain it and beat PSG to have a cup. Chelsea shown their strength against one of strongest clubs in Europe this season and they potentially can grow up more and become more competitive in a next season. Chelsea will be more ready to challenge many competitors for Premier League and Champions League titles. They are strong and ambitious enough to aim at big titles, not a top four in Premier League or quarter final / semi final in Champions League.