Haas' Romain Grosjean believes the thinner tread of Pirelli's 2019 tyres has been the source of the US outfit's under-performance on race day this season.
The qualifying speed of Haas' VF-19 on Saturdays hasn't been matched by an equally good from on Sundays, with both Grosjean and Kevin Magnussen struggling to keep their tyres in the optimal operating window.
Pirelli introduced its thinner tread tyres last year, running them in Spain, France and Great-Britain to combat overheating and potential blistering issues at high-speed tracks.
The thinner tread has become the norm this season, but Haas' 2019 contender is having a hard time adapting to the new-spec rubber.
"We think that's what's hurting us," explained Grosjean.
"That's the only explanation we have, but some other teams have done a much better job in getting them to work.
"Sometimes they work and you don't know why and you don't ask yourself why.
"It has happened to us in 2017 in Austria. We were flying, don't ask us, it just worked. We tried to repeat that, same number, same temperature – but never got the same.
"I wish Formula 1 was easy in that aspect and we could have a bit more fun playing around with other settings."
As Haas continues to work on its tyre issues, the team has brought a few updates to Baku to help with its performance.
"We've brought some new parts and we're hoping that's going to help us," he said.
"Obviously it's about getting the tyres to work. If that's not enough yet, we need to look at more, but it's definitely there."