You're right, I agree with you Lens lost by a big margin to PSG did a bit of a disservice to their position in the points table. Now Lins will have to secure a series of consecutive victories, which will enable them to regain their place in the points table.
Lens is only one point behind Marseille in the standings at the moment and it's not a big amount for Lens to chase him back, because what is clear is difficult for Lens and Marseille to catch up with is PSG, who are currently still at the top of the standings. So Lens and Marseille only have to compete to take second place because the first place will likely belong to PSG again this season, even though the points are still possible to catch, but when it comes to the strengths in the team, I think PSG is still far more from both Lens and Marseille.