The German manufacturer endured another challenging weekend in China where the promise of a second place in the sprint with Lewis Hamilton was not followed through to the main grand prix.
Russell came home in sixth, with Hamilton down in ninth, as the squad was once again left chasing answers about why it cannot unlock the potential it feels there is in its W15 car.
And with major set up direction changes for both drivers after the Saturday sprint failing to deliver any ultimate improvement in potential, the team concedes there is still an element of mystery about what is going on.
Team boss Toto Wolff said: “I think the car is a difficult car to set up and difficult to drive, and that is why you have these oscillations in performances, in my opinion.
“I think where the car is, and where Lewis’s car was, was certainly far away from the optimum and it is driving on a knife-edge.
“So, what is it? This is where we are. For Miami we are bringing new bits, and it will be interesting to see how they are going to perform on the car.”
Source: Autosport