The WO1 has problems. It has been suggested that the balance may be wrong. A persuasive argument was made that it is the insufficient stiffness of the tub is the problem. I noticed this picture and was struck by the front wing. The air has to be guided away from impacting the front tires head on. Mercedes are deflecting it away to the side. There are thus two (balanced) aerodynamic forces acting sideways to the car right at the front. However, when the car tries to change direction the angle of attack of the inside wing fence increases &, conversely, the outside one reduces. The nett effect is an increase in the aerodynamic force opposing the direction change of the car. The effect is greatest on high speed sweeps and least on low speed hairpins.
Now look at what some of the competitors do. They deflect much more air upwards over the tyre as against sideways around the tyre. That does two things – 1. Reduces the centering force & 2. Increases the downward force.
Ferrari
Red Bull (I looked for a decent overhead picture but failed to find one)
McLaren.
Renault.
I am no aerodynamicist but it was mentioned that the front wing is generating 2000N (per side?) of downforce and it seems that Mercedes is deflecting a lot of air sideways so the lateral forces are probably significant giving an understeering car.