The logic is as follows:
1) If you believe that the losses are due to strategic errors / playcalling / misuse of personnel - Then getting rid of PP/GDL should happen right away, so as to allow for others to try to change those strategic errors and / or personnel changes.
2) If you believe that the losses are lack of motivating players - Then getting rid of PP/GDL should happen right away, so as to allow for others with more fire in their bellies to come through (Hughes, Weist, Foley, Wholley).
3) If you believe that the losses are due to lack of recruiting prowess - Then getting rid of PP/GDL should happen right away, since losing any future recruit they might be closely in on would not be a great loss under that assumption.
4) If you believe that the losses are due to the inability to coach Edsall's recruits to the same competency as Edsall did - Then getting rid of PP/GDL should happen right away, since incompetent coaching will hurt the team more over the course of the season, not hurt less.
So if the question is, "What do you gain by letting them go now?", then I would follow that up with, "What do you gain by keeping them now?"...