Marseille is actually playing very well this season but they still have to improve so they can be better and can be a competitor than Paris Saint Germain at the top of the standings this season they are another class with dance in second place but overall they are playing quite well. Inconsistency is a nightmare for all teams, not just Marseille, Paris Saint Germain also feels the same way.
Marseille are good but not fine in Ligue 1. I mean they are doing good in most of the games played but they missed many opportunities to get closer to PSG and to pass Lens in the ranking. PSG missed too some games but this is just normal, they can't win all of them after all.
Marseille need to accept less goals. Building a better defence line is required. That is the difference between them and Lens. Scoring more goals will make them better than PSG. To obtain that, they need to spend more money

it's hard for Marseille to be able to spend a lot of money to buy players because the funds they have are very limited, especially since the prices for top players are so unreachable for them, apart from that it seems that PSG will not buy many players, they are more likely to just keep the existing players.