Michael Schumacher's collision with Williams driver Bruno Senna in Sunday's Spanish Grand Prix has once again focused awkward attention on the German legend's lacklustre performances for Mercedes.
A senior member of the Mercedes team used the word "mediocre" last weekend when discussing the 43-year-old's driving, and that was before Schumacher clumsily ran into the back of Senna's car in the race.
It was the sort of error you might expect from a beginner, not a man with 91 grand prix victories and seven world titles under his belt.
Coming at Senna from a long way back, Schumacher seemed simply to misjudge the closing speed of the two cars and, caught in two minds about which direction to go, he ran into the back of the Williams.
Schumacher called Senna an "idiot" on the radio as he sat in the gravel trap in the immediate aftermath, and, even after watching replays, he still seemed convinced it was his rival's fault. The stewards disagreed and gave him a five-place grid penalty for the next race in Monaco.
Schumacher's reaction will have surprised no-one in F1 - he has always seemed to lack the ability to accept he can ever be wrong.
In an aspiring young driver, this is a characteristic one might expect. But age is supposed to bring wisdom and, in this aspect at least, it appears not to be the case with Schumacher.
With the passing years comes an inevitable waning of physical abilities, and it is surely now beyond dispute that this has come even to him.
Michael Schumacher collides with Bruno Senna during the Spanish Grand Prix. Photo: Reuters
How long can he go on raging against the dying of the light? More to the point, perhaps, how long can Mercedes accept it?
There is no shame in Schumacher not being the driver he was - one can argue there is honour in him being able to achieve even what he has as he heads into the middle of his fifth decade.
The facts, though, are that he is now no more than a decent F1 driver - and some may argue not even that.
Statistically, this is the worst start to a season in Schumacher's career. But statistics can be misleading - Schumacher actually started the season well. He was the stronger of the two Mercedes drivers in the first two races.
But then came China and Nico Rosberg's qualifying lap, half a second quicker than his team-mate, who was second on the grid.
The gap was explained almost entirely by a stunning middle sector of the lap from Rosberg, which Schumacher, I'm told, justified to himself by Rosberg managing to turn his tyres on better.
That may well have been the reason, but the gap was there nonetheless. As it was again in the race, when that excuse was less justifiable. Schumacher was simply outclassed by his team-mate.
They have been more evenly matched since, but still Schumacher is almost certainly getting no more from the car than a number of other drivers could manage.
The contrast, with what Fernando Alonso is doing in the Ferrari - which is not dissimilar to the sort of thing Schumacher used to achieve in his early years with the team - is stark.
The tragedy of Schumacher's current situation is that it is leading some people to question his earlier achievements of seven world titles; two with Benetton and five with Ferrari between 1994 and 2004.
His criticisms of the Pirelli tyres after Bahrain drew uncomfortable parallels with the bespoke tyres from Bridgestone which Schumacher enjoyed for much of his Ferrari career, a subject that was largely unexplored during his pomp.
Some are beginning to wonder if seven titles really was such an amazing achievement, given the advantages he had at his disposal?
This would be wrong, though. There is no doubt that the Schumacher of the 1990s and early 2000s was an outstanding racing driver, one of the greatest there has ever been.
But that Schumacher belongs to the past.
The current one is out of contract at the end of this season. This, in fact, was the context in which the "mediocre" remark came up.
So what reasons do Mercedes have to keep him on, rather than try for someone else?
Lewis Hamilton, also looking for a new deal in 2013, may well not be available, or interested. Alonso, Sebastian Vettel and Jenson Button are committed to their current teams. Those left are all unproven.
Schumacher may continue to embarrass himself in wheel-to-wheel racing occasionally, but he's close to Rosberg's pace these days - and Mercedes' top management rate their younger driver very highly indeed.
The other reason is less palatable for those who like to consider F1 as the arena in which the very best drivers in the world do battle. It's commercial.
Schumacher's marketing value to Mercedes is huge. After Rosberg's victory in China, vice-president of Mercedes motorsport Norbert Haug delighted in how "fantastic" Schumacher had been in front of 800 guests at the launch of a new road car model in Shanghai the previous night. It had been, Haug said, "the perfect weekend".
Schumacher may no longer be one of the best F1 drivers, but around the world he remains arguably the most famous - and therefore the most valuable to Mercedes off the track. And in Germany, Mercedes' home, he is largely untouchable, voted recently the greatest national sportsman in history.
Ultimately, though, Mercedes are in F1 to win - and it is no secret that, after two disappointing seasons, the pressure on the team at the start of this season was enormous.
It will have been alleviated somewhat by their win in China, but the team have faded after a promising start and currently look no better than they did through much of last year.
In a season as topsy-turvy as this, that could easily change - and, who knows, if everything comes together perhaps Schumacher can win again. After all, who before the weekend would have predicted Pastor Maldonado's victory in Spain?
But, all things being equal, that looks unlikely. For a team with an average car who need to win, is a "mediocre" driver, however famous, good enough?