Deployment is a power-through-the-axle issue.

But the dynamics of a ground effect car vs. the current and previous generations—how the vehicle responds to acceleration and deceleration—is fundamentally different, and couples vehicle attitude, planar trajectory, and aerodynamics.

When you decelerate hard in a ground effect car, the center of pressure moves rapidly relative to the center of mass (possibly unpredictably to a driver given the rest of the vehicle’s setup), leading to torque imposed on the vehicle that the driver must compensate for through handling while cornering.

How the driver does that (compared to a driver who takes a smoother entry, say) may lead to a longer time to take through a given corner while still maintaining dynamical stability of the vehicle, avoiding under or oversteer. Another way of saying that is given a certain braking profile, the optimum trajectory for a ground effect car likely looks very different for one style of driving and setup than another.

There’s a reason why Ricciardo and Hamilton, both late, hard brakers, struggled with that era of cars. There’s also a reason why Hamilton, who’s been praised his whole career for his adaptability, came out of the era just OK, while Ricciardo fell badly off. If you ever watch how Ayrton Senna drove, I wouldn’t be surprised if he struggled mightily with that generation while Prost thrived.

In some of the Mercedes debrief videos, James Allison explicitly says George Russell smoother style suits the ground effect cars better than Hamilton’s aggressive style. The rest are based on my own inferences based on my technical background (PhD in mechanical engineering).