Williams technical boss Paddy Lowe insists the team are "very happy" with the way their drivers are performing, saying it's the car that is not up to standard.
The Grove-based squad have made a nightmare start to the 2018 season as they are the only team who are yet to score a point after three races. They have also come in for some heavy criticism for picking an inexperienced line-up of Lance Stroll and Sergey Sirotkin.
However, Lowe insists the drivers are "not causing any issues", it's the car that is not performing.
"When you are trying to develop a car, clearly the easiest would be to have a standard test with rather than a human – you try and do that with experiments in the lab," he is quoted as saying by Crash.net.
"And in the end everything you do with cars driven by real drivers, you have to factor in the quality of the driver, the effect of the driver, that took your interpretation of that car. And every driver is different.
"We have two different drivers that are relatively inexperienced. But we are very happy with what they are doing. And it is not causing us any issues and we would not allow that to distract from the fact that we have not produced a car that is performing correctly or as we would have intended."