In Ligue 1 PSG does not have a fairly balanced rival and they will continue to dominate the league forever. The difference in quality, club finances and resources possessed by PSG will be very difficult for other clubs to break. Now what PSG is doing is no longer talking about how they can get the Ligue 1 title but how they can compete in the Champions League competition. Because when it comes to Ligue 1 they don't need other great players and the quality they currently have is enough.
Luis Enrique has an obligation to manage the team and the big targets given to him are how PSG can compete in the Champions League. Their performance has not decreased and in fact I see it is much better after Luis Enrique became coach, but it is not yet fully optimal because it may take time for PSG to build a much stronger squad.
Say that to Bayern Munich, they're always become a champion in Bundesliga for a decade which mean in there there's no balanced rival too, but they're always become one of favorite in Champions League. Remember we're talking about no rival and Champions League, not only the current season since Bayern Munich now has a new rival i.e. Bayer Leverkusen.
PSG is just an all star club without any strategy, that's why they always lose against all star club that play with a strategy.