Former F1 driver Giedo van der Garde says Robert Kubica's future on the grid "doesn't look good".
After a long absence from Formula 1 following his 2011 rallying crash, the now 34-year-old Pole returned to the sport this year with Williams.
Some are hailing Kubica's renewed presence in F1 with his permanent arm injury.
"For me, Robert Kubica is the man of the race at every grand prix," Dutch GP boss Jan Lammers told the Dutch site racingnews365.
But van der Garde says the performance aspect cannot be overlooked.
"He is being beaten by his teammate in the same car," said the former Caterham driver. "So you can only conclude that he is not doing well.
"You can see that he is struggling with his arm and his hand, and besides that, a lack of racing rhythm in the sport has also hurt him," the 34-year-old added.
"Kubica had the right to give it a go, but you have to say that right now it doesn't look good."
