Button hurt by lack of car development

The British driver was outqualified by the Brazilian in five of the last six races of the season, and Barrichello scored 11 of the team's 14 points in 2008.

Honda had a difficult season as they decided to shift their focus to 2009 very early, with very little development work done on this year's car.

Brawn reckons the lack of improvements hurt Button and may have helped Barrichello being the stronger driver.

But the team boss reckons both men are closely matched.

"I think they are both quite close in performance and they gone up and down over the whole year," said Brawn. "So I don't know what to put it down to. Jenson has not been finding the balance with the car that he is happy with, for sure, and I think Rubens has been able to hit the sweet spot with the car a bit more.

"And if I am frank we haven't been doing anything with the car so perhaps the car has moved a little bit away from one driver and towards another, as it has evolved we have not done very much to correct that, but there is nothing specific I can put it down to."

"I am not surprised because I know Rubens is a very fast driver, possibly the lack of evolution of the car has meant a car has been more towards one drivers' style is not something that we would have changed during the year, in normal circumstances you would be listening to drivers' comments trying to listen to where they are losing and improve things.

"Because the braking system on this car will be the system we have next year it was a valid area to improve and we have improved the braking stability on the car, and that was an area Rubens was particularly sensitive to but not Jenson because of the way they brake and enter a corner.

"So you can see some areas where we have developed the car that have been more beneficial to Rubens but the fact we have not had an intensive development programme may have hurt Jenson because the things he needed from the car we haven't done much about.

"They are both pretty good drivers, and when they have both got the car working for them they are pretty close I have no doubt."

Button will remain at the team next season, while Barrichello's future is still in doubt, with Honda set to evaluate Bruno Senna this month.

Brawn said there is not schedule for a decision on their drivers.

"There isn't one, to be honest. We just need to know before the first race. There is no fixed timetable and we will make a decision when we have all the right pieces of information."