The poet Patrick Kavanagh once observed that "posterity has not printed its banknotes yet", but tentative judgments are already being made on Michael Schumacher's baffling decision to return to Formula One, the sport he dominated with such ruthlessness in the vivid colours of Ferrari.

When the three-times world champion Niki Lauda was asked about Schumacher a few weeks ago he said that opinions should be reserved until after the third race of the season, which took place in Malaysia a week ago.

Schumacher, after all, had shown a complete mastery of Sepang's wide open spaces, winning there in 2000, 2001 and 2004. But, last Sunday, the German, who had qualified in eighth place on the grid, retired after nine laps.

After three races, his best finish has been sixth and he has failed to qualify better than seventh. This is the man with 91 victories and 68 pole positions to his name. It has not gone well. and his Mercedes Silver Arrow has looked about as sharp as the sort boys used to play with, with a piece of rubber at the pointy end.

At 41, he is stalked by Anno Domini and by his own legend. And he has been beaten not only by other teams, but by his team-mate Nico Rosberg, the scion with the looks of the young Leonardo DiCaprio, who won the team their first podium finish in Malaysia.

Schumacher is also one of only two drivers – Russian rookie Vitaly Petrov is the other – to have been out-qualified 3-0 by his team-mate this season. Little wonder the German newspaper Bild recently ran the headline "Der Schumi‑Absturz" – the fall of Schumi – amid growing speculation that the driver may not see out his three‑year contract with Mercedes. With sponsorship, he is earning £29m a year.

It is not only in F1, of course, where bright young things show a marked reluctance to genuflect before their elders. But Schumacher has been dismissed with something of the hauteur he once paraded in the pit lane.

There was something a little sad about his protracted tussle with the Toro Rosso of Jaime Alguersuari, the youngest driver to take part in F1, in Melbourne, though he wouldn't thank you for the sympathy.

The three times world champion Jackie Stewart has his doubts about Schumacher's ability to win another world title. "The jury's still out," he says, sounding dubious. "It's very clear that Michael has not lost any of his skills. You don't just check out from the experience and knowledge that made him champion seven times.

"I remember that five and 10 years after I retired, when I was 39 and 44, I came back to drive all the cars in the championship on behalf of Elf and I didn't feel that I had lost anything. But Michael has not been able to deliver on the pace yet and the fact that he has been beaten in qualifying and in the races by his team-mate will trouble him more than he has shown."

According to Stewart, this is not only down to his car, but to the talent that surrounds him on the grid. "Jenson Button and Lewis Hamilton are both fantastically fast at McLaren.

"Then you've got Felipe Massa and Fernando Alonso at Ferrari and the Red Bull pair of Mark Webber and Sebastian Vettel. But outside the main teams you've got drivers as good and as experienced as Rubens Barrichello and Robert Kubica. It's the best group of top drivers that I can remember."

Stewart has enormous faith in Ross Brawn, the man who guided Schumacher to his first two titles at Benetton and then five in a row at Ferrari. "The Mercedes will improve. But then so will the other cars."

The mistake Schumacher has made, according to Stewart, is not coming back but retiring in the first place. "Michael retired too early. He shouldn't have quit because he hadn't finished with it.

"I knew I wouldn't race again when I retired and so did Gerhard Berger. When Niki Lauda finally retired – after a successful comeback, mark you – he even left his helmet on the seat of the car. He knew, we all knew, that he just wasn't going back there. But Michael always had unfinished business."

But Schumacher is still giving value for money according to Stewart. "The sponsors are getting their delivery because Michael will be good news at every race this season. Wherever he goes he is making a comeback and the cameras are rolling."

Meanwhile, Mercedes bosses are still convinced about their man. "As soon as the car can win so can Michael," says Mercedes-Benz motorsport boss Norbert Haug, while chief executive Nick Fry insists everything is coming together. But others maintain that three years is too long to be out. And in the fast evolving world of F1, to merely stand still is to be hurtled into history.