Robert Kubica can't expect to land a race seat because of his past form according to Williams chief technical officer Paddy Lowe, who says the Polish driver must earn a seat on the 2019 grid if he's to fulfil his comeback dream.
Kubica was in the running to return in 2018 with Renault at first before that gap was filled by Carlos Sainz. An opportunity to replace Felipe Massa at Williams then arose, but following multiple tests, the team opted for Russian rookie Sergey Sirotkin.
Lowe admits Sirotkin was the "clear favourite" when all factors were taken into account, but wouldn't elaborate on which areas Kubica was lacking.
"I'm not going to talk about that," he told Motorsport. "We've done a lot of work with many drivers in this selection process.
"We picked Sergey on the full range of his performance, against many drivers, not just Robert. He was the clear favourite."
Kubica will take up a reserve and development role with the team which will include test outings as well as Friday practice runs, which Lowe says will give the 33-year-old a chance to prove them and other teams that he is deserving of a seat.
"Robert has been on a journey to find his way back to Formula 1, from the trauma that occurred to his arm in the rally accident.
"And all credit to him, it's required an incredible commitment, a lot of bravery and a lot of dedication to that objective. And he's on that journey, and I think with us this next year as the development driver that journey will continue.
"Ultimately, it's not always about what's missing – it's a competitive market, to obtain a race seat. There are many more very, very talented drivers than there are seats.
"And Robert would want it no other way. He's got to earn the right to the race seat, whatever race seats may be available in 2019."
