When Sebastien Bourdais' 18-month Formula 1 career quietly ground to a halt with a hydraulic failure on lap 19 of the German Grand Prix, few in the paddock took much notice. Most had written him off long ago. The same old story, they said. Yet again, a big fish in a small pond, an American open-wheel superstar, had been exposed as a very average fish in the only pond that mattered. Like Michael Andretti, Cristiano da Matta and Alex Zanardi before him (this line of reasoning tends to ignore the success of both Jacques Villeneuve and Juan Pablo Montoya, who did convert their Champ Car titles into F1 success), he showed that victories in North America mean nothing in the rest of the world.

But to those who saw Bourdais – nicknamed "Seabass" by his U.S. fans – in his Champ Car pomp, when he won four consecutive titles during a five-year spell with Newman/Haas/(Lanigan) Racing, or those in Europe who paid attention to his success in junior single-seater categories and sports cars, his F1 failure is more puzzling. To them, it's not so easy just to write him off as an also-ran, as merely a very good driver among the great. So how do you explain his record of just four top-10 finishes and six points in 27 F1 starts?

Arguably the man in the best position to judge is Scuderia Toro Rosso technical director Giorgio Ascanelli. An engineer unusual in that he firmly believes that drivers make the difference – not surprising for a man who has worked with Ayrton Senna, Nigel Mansell and Nelson Piquet – he is damning in his faint praise of Bourdais after working with him for a season and a half.

“I don't think Bourdais is a World Champion,” says Ascanelli. “When you find a World Champion, you recognize him but Bourdais is an average professional. Has he had it easy? No.

But you do not expect a driver coming from his success in Champ Car to be outqualified seven times out of nine by a rookie [his teammate Sebastien Buemi]. I'm not slagging him off, and I think he could have become better. But I don't know whether he would have.”

It had all started so promisingly. Early last year, he seemed to have the edge over the “the new Schuey.” While teammate Sebastian Vettel racked up four straight DNFs, Bourdais, who was denied fourth place on his debut with a driveshaft failure in Australia, looked very at home in Formula 1. He was – and therein, peculiarly, lies the problem. The Toro Rosso STR2B was very much to his liking, being both predictable and well-balanced. Then came the introduction of the STR3 at Monaco and, two races later, a major upgrade package from Red Bull that Bourdais didn't like.

“You have oversteer in the slow corners, massive understeer in the high-speed corners and you have a half-decent in between,” said Bourdais after a couple of races with his new machine. “But I don't do well with oversteer at slow speed and I don't do well with understeer at high speed so I get the short end of the stick and get pretty badly kicked. It has always been my problem.”

This meant that Bourdais was lacking that last percentage of commitment to a corner in qualifying. The real problem was that, by contrast, Vettel was untroubled by the change in handling characteristics. Asked about his teammate's difficulties, and the German would simply shrug and say, “It's no problem for me.” From this point, Toro Rosso's and Vettel's fortunes skyrocketed, while Bourdais' slumped as he lost confidence in the car. From the German Grand Prix onward, Vettel was always a  top-eight threat, and took that sensational win in the Italian Grand Prix at Monza. At year's end, he had 35 points, Bourdais had just four.

It wasn't explicit, but Bourdais clearly felt that the team's focus had switched firmly to Vettel, but given the disparity in performance between the two, who could blame them?