If Robert Kubica required statistical evidence of the fickle nature of Formula One, he need only compare the standings after six races last season with those going into the seventh round of the current title chase in Turkey on Sunday.

This time last year Kubica had 32 points, 29 more than the struggling Jenson Button, and was about to claim a maiden Formula One win in Canada that would temporarily propel the Pole to the top of the championship table.

Such was the potential demonstrated by Kubica and his ever-improving BMW-Sauber team that going into the 2009 campaign the BBC's Martin Brundle proclaimed: "You've got to fancy BMW as very strong runners."

Alas, even the best pundit in the pit lane can get it wrong. While Button's fortunes have been transformed by an ultra-competitive Brawn GP car, the Briton taking five victories from six starts to dominate the championship with 51 points, Kubica has yet to get off the mark. He has not even finished in the top 10.

It is the same story in the constructors championship which Brawn GP lead on 86 points, 80 ahead of BMW who languish eighth only just in front of Toro Rosso. And the nightmare shows no sign of abating.

In Monaco a fortnight ago, Kubica was 17th on the grid immediately behind German team-mate Nick Heidfeld, who described the team's worst-ever qualifying performance as "dismal".

Team principal Mario Theissen admitted: "Ahead of the Turkish Grand Prix our results are quite sobering."

Kubica agreed, saying: "We have to realise that we are bad."

That is a damning indictment on one of the sport's best funded and best equipped teams - a unique supercomputer at BMW's Hinwil base in Switzerland, for example, is capable of performing a staggering 12.2 trillion calculations per second.

What it clearly didn't compute was the possibility that the white and blue cars would suffer a distinct lack of grip and dire aerodynamic performance.

Theissen conceded: "Nobody in the team expected the season to pan out as it has so far. The problem is that for the last three years we have shown a continual upswing in results and this is our first real step back. We have to gather ourselves and work through it. And that is what we are busy doing."

Like McLaren and Ferrari, Theissen's outfit was caught cold at the start of the season by Brawn GP's controversial double diffuser.

But as Kubica ruefully pointed out, McLaren and Ferrari reacted quickly once the diffuser was declared legal by the FIA, with a resulting improvement in results. BMW will only introduce their version of the aerodynamic aid this weekend.

Kubica said: "At the start of the year McLaren were much worse off than us. But after the FIA allowed the double diffusers, they overtook us. It seems they simply can develop faster and adapt better."

He now admits to a fear that last season may have presented him with his only chance of the championship. "I don't know if next year I will be in Formula One," he said.

Kubica is still smarting from BMW's decision to stop developing their car well before the end of the 2008 title fight in order to concentrate resources on 2009, with the result that McLaren's Lewis Hamilton and Felipe Massa of Ferrari were able to streak ahead.

He said: "I have done pole position, I have won a race, I have been leading the world drivers' championship standing. But in the end, none of this matters. All that matters is the championship.

"That's why I was disappointed last year when we did not seize our chance when we were very close to the front. You have to seize your chances."