Baup also believes that the game could have been different had Andre Ayew not struck the post in the second half.
"We had a very good first half," Baup said in his press conference. "The match was very open and we tried to get forward and play our game.
"But the goal we conceded at the beginning of the second half really hurt us. If Andre Ayew had scored instead of hitting the post, that would have changed everything.
"But we ended up dropping our rhythm and leaving space at the back, and against a strong side like Monaco, you pay dearly for that. I hope that next time we can maintain our rhythm for the full 90 minutes. That's our objective."
The defeat was Marseille's first of the season.