If the step forward that Ferrari took this year was something of a mystery, so too was the obvious step backwards since the summer break.

Sebastian Vettel's self-inflicted issues aside, the sheer grunt of the Ferrari witnessed at Spa and Monza - where the Mercedes was effectively left for dead - suddenly went missing.

Though some have attributed this to a second sensor the FIA fitted to the SF-71H's energy storage system, others point to the fact that the COTA revival follows the removal of a raft of updates introduced in the previous three races.

Whatever, Sebastian Vettel believes it is too little, too late.

"It took too long," he says. "You can see it as good news but you can also see it as bad news. If we have to go back to a car that has been competitive three or four months ago, surely it can't be good news if you think about it."

Asked why he thinks Ferrari has struggled in recent races, the German replied: "It's a bit hard to explain. If you don't see that there is a problem, you don't think that there is a problem.

"We felt the car was not as strong as it was before but if you don't see there is anything wrong then you don't know that there is something wrong. All the steps we did, they seemed to make sense. But now looking back, they didn't.

"Clearly there was something missed," he admitted. "We haven't understood why and where the error started, there is a lot of stuff for us to do and understand, but I'm pretty sure we will do what is necessary and get on top of it.

"It is not like there is a fundamental problem, and in the end it looks a lot worse than it was," he continued. "And I have no problem admitting the mistakes I've done on top.

"I think there were some things that happened to us that didn't help us. But I think the crucial bit has been that for a big part of the season we didn't have the speed to really be there, and then other stuff happens that maybe doesn't help that. I think overall we have the potential. I think we need to still grow and learn. So I think there will be a lot of stuff over the winter that we need to review, all of us, including myself."

Check out our Sunday gallery from COTA, here.