what? Downforce dynamics, the predictability thereof (as a function of yaw/steer i.e. no points of discontinuity in reactions to yaw/steering at any speed, only gradual changes)? I just wonder what's the measure of yaw/steer sensitivity when working in a theoretical environment like with CFD (in the preproduction, conceptual, planning stages). There must be some pretty well understood and established criteria if that's where "most of the job is done".
What he means by sensitivity is change in downforce with respect to yaw angle, with the goal being as little loss in downforce with increased yaw. When a car is cornering, there is an angle between the actual vehicle heading and the direction that the nose is pointing, this is the yaw angle. It is a function of tire slip angles and can vary with change in lateral acceleration or turning radius. Its important for the front wing to maintain a consistently high level of downforce at all reasonable yaw angles so that its performance does not suffer in certain types of corners or with certain types of tires (dif compounds or rain tires).
Also, if the front wing, or any other aerodynamic components for that matter lose downforce at yaw angle then when a driver makes a slight mistake (ie:oversteer bobble) it will be much harder to regain control because of the instantaneous loss of available grip.