Got it... But still I am trying to clarify something else...
We all understand the intent to clean up the air behind the cars to allow them to run closer together and overatake more easily, that explains the loss of all the silly winglets and the taller rear wing.
Does not explain the narrower rear wing and the wider front wing which seem taken together that the intent was to create more downforce up front and less at the rear..
Am I missing something?
As for the diffuser, it's all about volume and suction capability, remember these cars have flat bottoms.. so the only way to extract air from under the car is by using diffusers at the rear and what matters is the volume not the placement.