As Michael Schumacher approaches the third season of his grand prix comeback, with not so much as a podium place to add to the seven world titles he won during his first incarnation between 1994 and 2004, Ross Brawn is pondering a little matter of three-tenths of a second, representing the average margin conceded by the 42-year-old former champion to his Mercedes team-mate, the 26-year-old Nico Rosberg, throughout last year's qualifying sessions. If Schumacher is finally going to justify the enormous financial and marketing investment in his return to the track by regaining the victory habit, where he is he going to find those vital three-tenths?

"Maybe he doesn't," comes the surprising answer from Brawn, who knows more than anyone in the Formula One paddock about Schumacher the competitor. "Maybe he lives with it and uses his experience and knowledge to compensate."

Speaking before his departure for Melbourne, where the season opens with next weekend's Australian Grand Prix, Brawn brushes aside the suggestion that Schumacher might have lost his edge. It is not, he said, a matter of something as simple as the courage and self-belief required to take a 180mph bend flat out in seventh gear.

"If Michael were feathering the throttle in fast corners and not confident about his ability to deal with it, you'd say, well, clearly, you can see it's slipping away from him. But you don't see that – in fact often he's the same or even quicker in the fast corners. Nico just seems to have more of an intuitive ability to get the most out of the tyres on one lap.

"In the races, where it's a more consistent process, there's nothing to tell between the two of them. There are some races where Nico's dominant and some where Michael's very strong. I don't know if he will find the difference in qualifying, because Nico is very special in those circumstances, one of the best I've seen. At the moment Michael hasn't understood how he can get that."

The pace of technical progress in Formula One is unrelenting, and things have changed considerably on the tyre front since 2006, when both men left Ferrari, Brawn to spend a couple of years' sabbatical with his fishing rod and Schumacher embarking on what turned out to be a three-year retirement. "We still had grooved tyres, and there was a tyre war going on between Bridgestone and Michelin," Brawn says. "We were the main Bridgestone customer and the tyres had been developed with a large input from Michael, so naturally they suited his style and approach."

When Schumacher returned, it was to a world in which the rules said that all drivers had to use the same rubber. "Now there's only one tyre out there, it's the same for everybody, and he's got to work out how he's going to get that performance from it," Brawn continued. "There's no testing, or very little, so you can't go out there with 10 sets of tyres and say, right, I'm going to do one lap on each set and work out how to squeeze out that last little drop.

"Perhaps the tyres have evolved in a way that suits some drivers more than others. Nico is quite exceptional in that respect, and he's a great asset to the team. I think when he wins a race, you'll see another step in his performance."

Brawn saw that happen to Jenson Button, his other world champion, in 2009, when the team now known as Mercedes was briefly called Brawn GP, having risen from the ashes of Honda's withdrawal. "Jenson had won a race before, in slightly odd circumstances. But when he started to win races because he was the fastest driver in the fastest car, he changed. He became far more consistent and we started to see the driver that he is now. When Nico gets into that position I think we'll start to see things from him that we didn't know he could do."

Meanwhile the rest of Formula One looks with surprise on the underachievement of a team whose drivers have failed to make a dent in the supremacy of Red Bull, McLaren and Ferrari. A couple of fifth places were Rosberg's best finishes last season, while Schumacher – the winner of a record and probably unsurpassable 91 grands prix – managed a fourth in the wet in Canada.

In the terms with which Mercedes is familiar, this is simply not good enough. If Ferrari is the most glamorous name in grand prix racing, with the longest continuous involvement in Formula One, that of the German team is the one that traditionally inspires awe. Their cars have been around since the days when pneumatic tyres were a novelty, and their participation was virtually synonymous with victory.

Sitting in his office in Brackley, almost within earshot of the racing engines at Silverstone, Brawn remains the most successful team boss of the modern era, but he seems far removed in place and time from the legendary figures who presided over earlier eras of Mercedes dominance. These include Max Sailer, installed as technical director after driving in the famous French Grand Prix of 1914, when a clean sweep of the top three places by the German cars brought down the curtain on the Edwardian era of motor racing; Alfred Neubauer, who invented pit signalling and managed the team with an eye for the smallest detail; and Rudi Uhlenhaut, the head of the experimental department, who often took the Silver Arrows of the 1930s and 1950s out on tests and was said, even in the Fangio era, to have been capable of producing laps as fast as those of his top drivers. Clearly it would not be desirable for their English successor to be the first to fail.

"That's true," Brawn says, with a slightly rueful laugh. "I think if the team doesn't perform over a long period of time, you have to accept the consequences. You're here to represent the history of Mercedes. It's one of the iconic brands, and if you damage it then the whole project won't be attractive to the board. They've said, and I share their opinion, that fourth place in the championship is not what we want to achieve.

"Where I take comfort is that Mercedes have now been in Formula One in this era for almost 20 years, admittedly mostly as an engine supplier but also as a high-level shareholder in McLaren for a number of years. They lived with the ups and downs and didn't falter when things got difficult. As a company they don't flap around in the wind. They've got stamina and they understand that things are built over time. They're passionate about the sport and where it fits into the company. That gives me faith."

In order to bolster their belief in his ability to create a winning team, he spent last year adding senior engineers to a structure that was stripped to bare bones when Honda suddenly pulled out at the end of 2008, leaving Brawn and his colleagues to devise a management takeover. Lack of sponsorship meant that an organisation of more than 700 employees was suddenly cut by almost half. Now it is back up above the 500 mark, the newcomers including three highly experienced technical figures: Bob Bell from Renault, Geoff Willis from Red Bull and Aldo Costa from Ferrari, joining the chief designer, John Owen.

But is their WO3, the car that will appear at Albert Park this week with the familiar three-pointed star on its nose, really a Mercedes-Benz or just the product of a bunch of UK-based engineers who happen to be wearing Mercedes overalls?

"You can't suddenly flick a switch," Brawn says. "I'd be lying if I said that from the point we became Mercedes there was silver blood running through my veins. It's a transition. It takes a while. But I've got to know the board and how passionate they are about the history of Mercedes. Now I'm proud of it, and the reigniting of the history of Mercedes as a grand prix team is something I've grown very passionate about. You're holding the lantern for a while, and it does carry certain responsibilities. I want to be part of the history of Mercedes."