Three races in and the doubters are gleefully gathering evidence. Their case may as yet be not proven, but the initial charge of ignoring one of sport's lasting truths stands. Never go back, especially if you are already a multiple world champion with more race victories than you can shake a gear stick at.
Michael Schumacher had no further mountains to climb after a brilliant career that, statistically at least, wiped the floor with everyone else. Seven world championships – two with Benetton, five with Ferrari – eclipsed even the legendary Juan Manuel Fangio's five. Victories in 92 grands prix matched the combined scores of his closest rivals, Alain Prost with 51 and Ayrton Senna with 41. When he retired at the end of 2006 he had nothing left to prove.
And yet ... when Felipe Massa was injured during qualifying for last year's Hungarian Grand Prix, Schumacher jumped at the opportunity to stand in – until a neck injury sustained during a motorcycle crash in February stymied him. It seemed that one of those sublime moments in sport was not, after all, destined to happen. The champion would not come back to put the young lions in their place. But then Jenson Button quit Brawn GP after winning the 2009 world championship, and as the team metamorphosed into Mercedes GP, Ross Brawn pounced. Schumi was back, looking refreshed and supremely fit even at the advanced age of 41, and the sporting world was alive again with delicious expectation.
This was Schumacher! The greatest! It was not hard to get caught up in the excitement of a legend being given the chance to add another glorious chapter to his story. But there are no fairy stories in Formula One, as Schumacher's performance thus far has underlined. Of course it was the great man in the cockpit; there was no mistaking that prognathic jaw, but it was not, it seemed, Schuey in the lap times. In the first three races he was drubbed by his younger team-mate, Nico Rosberg.
"I've been around long enough to know what I call the wave of emotion," said Schumacher yesterday. "During the winter everybody was very emotional and very supportive and positive and once you're up on this edge of the wave, there's a natural happening that you start to fall over the edge – and whether you are the reason for it, or whether it's just a natural happening, it's not always important.
"The results have not been as great as some people have expected and even myself, yes, I would have loved to have better results. But the competition is very high and in this respect it's a natural happening to not have the same positive feedback in the media. But you know, I know exactly what I've been doing, I know what's been going on and I've no reason from my side to be disappointed, quite honestly. I still feel very happy. Whether people like it or not is their own choice."
The younger Schumacher could never have been as outwardly relaxed as the 41-year-old version has appeared in these circumstances. This, after all, is the man who would rage whenever a team-mate beat him, even in a test session, a driven personality who always had to be quicker than anyone else. It's hard to imagine that playing second fiddle to Rosberg hasn't dented his towering pride. "It depends what age you're talking about," Schumacher says easily, "because when I came into Formula One I would obviously have been very happy with the results we've had. If you talk about after winning certain championships, then naturally you would have been a little bit less happy, but with having all this kind of experience, coming back after this break, I feel more than happy with what's going on.
"One of the interesting things is working with the team to develop the car and being involved in that process. That is so much of the fun. The driving is fun as well but you get used to it pretty quickly, but working on the details, that's what makes it for me."
Ah yes, the details. Such as the fact that he and Rosberg drive a car that still has weight distribution problems, and a tendency, especially thanks to the narrower Bridgestone front tyres, to understeer. Schumacher hates an understeering car, and famously likes one that turns in if you so much as breathe on the steering wheel, and the hell with the ensuing oversteer exiting a corner. His other-worldly car control always enabled him to handle that better than his team-mates.
Now the boot is on the other foot, and to make matters worse Rosberg weighs 4kg less, which means he can move a similar amount of ballast around the car to optimise its poise. Schumacher lost 2kg early in the season, but with a more muscular frame than Rosberg's the chances of discarding more are limited.
Up until last week the German press had been benign, but then a journalist on Bild, their equivalent of The Sun, uttered the heresy that he will not win a grand prix this year. And there have been tales of monumental tantrums in the garage. One observer remarked: "You get used to these things in Formula One, especially in the heat of the competitive moment, but the tirades I saw early on were memorable for their scale."
And the man who deliberately parked his Ferrari at the Rascasse corner during qualifying in Monaco, to frustrate Fernando Alonso's chances of taking pole position, was irate enough to remonstrate with the Spaniard, and Lewis Hamilton, about their driving tactics in Melbourne, accusing both of blocking him in qualifying.
"I was slowed down by Alonso," he said. "I asked him whether the team had told him I was on a quick lap and he said no. Then I had a conversation with [race director] Charlie Whiting about it because I wanted to know what are the guidelines here – and whether the rules have changed.
"I had a similar issue with Lewis; that he was adapting his lap and preparing his lap and blocking me in a way – which is not very nice."
This generated widespread derision from those who remembered the ruthless tactics Schumacher used so blithely in his title quests that they led to collisions with both Damon Hill and Jacques Villeneuve. And proved that, in one respect at least, the leopard's spots remain unchanged, for Schumacher always courted controversy. But is the speed really still there or has he been left behind by the passage of time?
"It's natural that there are some characteristic changes but at the end of the day, every year, you get a new car, and you just adapt and work the car around your needs," he insists. "Yes, it has taken a little bit of time after being out for three years, it does need a little bit more time, especially with less winter testing available. But I'm feeling pretty good. It's worked out almost quicker than I expected and I feel very comfortable in the car and look forward to when things get to the end to show a little bit better."
Is this whistling to keep up a flagging spirit, or is he really as chipper about his future as he sounds? Schumacher has never been able to mask his true feelings. The optimism is genuine. If Mercedes give him the right car, he believes he can do the business in the cockpit. He knows all the little factors that go to make up the performance equation. How currently the window in which the vagaries of weight distribution and aero balance can be harmonised is so small that in a race the performance of the car can fluctuate dramatically to his detriment. And he believes he can still vie for a remarkable eighth title despite the disappointing start. "Look at the points system and how it works. You can have a retirement, the way that Fernando did in Malaysia, like I did there, and it is highly probable that the other guys fighting for the title will also hit trouble at some stage.
"We need fast development pace, and if we can achieve that there is no reason why we can't fight for the championship. We are only at the start of a very long season. Development is crucial, and we all know that the rate is fast. We have great potential to develop this car, so of course I'm not taking the view that the season is over, for either myself or Nico."
Optimism, or a solid opinion based on weighing up all the factors? "Michael needs to prove it by Barcelona, the clock is ticking," says the German writer Michael Schmidt. "But he is such a poor actor that if that's what he says, you have to think that's what he genuinely believes."
Slow off the grid: Schumacher's season
*Bahrain Grand Prix (14 March)
Schumacher qualified in seventh in his first competitive drive for Mercedes, before managing to rise to sixth during the race proper.
*Australian Grand Prix (28 March)
An early tangle with Fernando Alonso proved a set-back after Schumacher again qualified seventh. Struggling to recover, he surged from the back to clinch a points-finish in tenth.
*Malaysian Grand Prix (4 April)
The German started eighth on the grid after a rain-soaked qualifying. After making up two places in nine laps, he was left frustrated after being forced to retire with wheel problems.