The final match between PSG and Inter Milan was indeed a surprise to many people, especially since the score was also unusual, namely 5:0. It was something that was unimaginable before the match and even the finals that have occurred in the Champions League have never had a score that much. So PSG cannot be understood by all the teams that have faced them last season, namely the teams you mentioned, and I hope PSG can continue like that next season with some improvements because overall PSG's performance is clearly quite extraordinary when compared to other teams.
Before the game nobody would have agreed that inter will concede all that goals, it's surprising indeed, but looking at the playing pattern of PSG; absorbing pressure and using it as an advantage for counter attack, Inter had no chance. However, the technique is not hidden, every team knows about the way PSG operates in the midfield, yet can't figure a way out on pitch. So the club conceals and interswitch lot of structural information from what the media already knows.