Jarno Trulli says inconsistency was the main reason the departing Toyota team failed to achieve its potential in what turned out to be its final Formula 1 season.
The Italian was expected to part with the team even before it announced it was withdrawing from the sport, and speaking to reporters shortly before Toyota's exit was confirmed, he put its 2009 failure down to unfathomable fluctuations in form.
"In my opinion we had too many ups and downs," said Trulli.
"We started very well, but then we lost momentum, especially mid-season when coming back to Europe everyone made quite a big step and we hesitated, or probably we went wrong.
"Something definitely happened and we were not where we were at the beginning of the season.
"Then eventually at the end it came back.
"No one knows why, it's all probably related to the tyres."
The 2009 season was incredibly topsy-turvy throughout the field, but Trulli reckons Toyota's pace was the most unpredictable of any team's.
"You cannot start on the first row in Bahrain and the last row in Monaco - I was really frustrated then," he said.
"In general there has been a trend in the paddock for a lot of ups and downs, but we look like we suffered a bit more - sometimes really strong performances and then stepping back really quite a bit."
However Trulli does not think Toyota missed any real winning opportunities this year, even when it swept the front row in Bahrain.
"When you want to win a race, unless you have the best car, you have to have everything [perfect], and we didn't have it this year," he said.
"You have to capitalise on a bit of luck, and when it was needed we probably didn't have it.
"In Bahrain we had a very small chance, but you cannot say we threw it away.
"In the end we played our cards and we finished third, which was more or less the place for us to finish.
"We could have finished second, but if you look back on the race and the lap times that Brawn was doing, our position was second or third.
"So we came very close this year and I'm really happy that several times we were fighting for pole position, which showed the car has been generally competitive."
Team boss John Howett made it clear before the end of the season that Trulli was unlikely to be retained whatever the team's future held, and although the Italian was baffled by this, he accepted it was Toyota's right to make such decisions.
"To be honest I can hardly understand it," he said.
"The team has got the freedom to decide on drivers, and I do not argue with that.
"On the other hand, I think the team has to be really good with their drivers and with the atmosphere inside the team until the end of the season.
"Before the end of the season, you might say 'okay, we are not going to stick together' - fair enough, there is nothing wrong with that."