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 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."
Russell suggests that the way that major set-up changes over the China weekend did not yield much difference in performance points to the fact that Mercedes may need to accept that the car is delivering all that it is capable of right now.
"We've had two different set-ups this weekend, both of which produced very similar lap times and performance," said Russell.
"So, the work needs to be back at the factory and ultimately in F1, the more downforce you have, the faster you'll go. The set-up is the cherry on the cake."
From Russell's perspective, Mercedes needs to move away from analysis of finding a perfect set-up and go back to the more standard approach of focusing on aggressive development and a run of upgrades.
"I think there is no silver bullet," he explained. "We just need to keep on adding performance and focusing on the basics, which is in the wind tunnel and in the CFD: just adding downforce. Maybe sometimes it's as simple as that."
Russell said that so much experimentation and direction change had taken place throughout the ground effect era to settle on what the team has now that perhaps it had reached a ceiling on what is possible with its current equipment.
"I think we've understood enough so far that we just need to add downforce," he explained. "We've changed philosophies and we've changed concepts quite a few times now over the last two years.
"My personal view is that no matter what concept you're on, you just need to have as much downforce as possible, and you'll deal with the limitations thereafter.
"So yeah, let's see in Miami. We've got some upgrades coming to the car. Let's see what we can do with that."
