Alex Wurz has claimed that the aerodynamics on Williams's 2018 car are basically "stalling".
"We lose downforce to the diffuser," once team driver and now Williams advisor Wurz is quoted as saying by Italy's Autosprint.
"We had this problem last year but it was just annoying. Now it's stalling.
"We lose grip and the drivers have no confidence in the car."
Worse still, Austrian Wurz said that there is not yet light at the end of the tunnel for Williams.
"Identifying the problem is just 10% of the question. Resolving it is the real challenge," he said.
The team's performance so far in 2018 has left it bottom of the team rankings with four points.