Coming into the current season, everyone was initially confident that it would be another easy run to title victory for Mercedes and for seven-time world champion Lewis Hamilton. But that hasn't proven to be the case.
While major improvements in performance and reliability made by their Red Bull rivals have been a major factor, Hamilton says that tweaked aero rule changes affecting downforce brought in before the start of 2021 also played a major role.
Hamilton explained that the changes had interfered with Mercedes' development flow and left them scrambling to adjust to the new requirements.
“Definitely," he told a select group of media including journalists from the BBC, The Race and Motorsport.com during a wide-ranging interview in Qatar last weekend.
“The car has been very, very hard to set up. Toto said one of our cars was a diva, but this one is a monster of a diva.
"We knew we were going to lose all this downforce, and once we found how much downforce we lost the whole characteristics of the car shifted.
"What we had worked on for several years - getting the car into that sweet spot like last year - it’s been a nightmare to undo, by playing with the tools when you can’t actually change any of the tools.
"It just is what it is, and trying to find smart ways to work around less downforce," he said. “There have been a lot of elements that have made it harder than ever. It’s been the hardest car to set up.
"I’ve done a lot of sim testing but even sim days, you go and do a sim day and the sim is not in the right place it’s supposed to be," he continued. "The grip level’s not right, or the wind effect is not right, or the thermal deg is set wrong so you can come away with bogus numbers.
"You have to be so careful with the data that you are receiving and the decisions that you’re making. It’s been a rollercoaster ride.”
There have been other factors affecting the team's progress this yea, from a reduction in available track time to the ongoing effects of the COVID pandemic.
"We’ve had less practice time so it’s been harder to get the car in the right window," he noted. "Therefore when you don’t get the car in the right window, you just limit your potential.
"I’m just not able to maximise my ability through the set-up not being in the right place, and it’s been very, very hard to get it into the right place."
Hamilton said that getting everything right in Brazil - where he stormed trough the field form the back of the grid in the sprint race and Grand Prix - had been "like literally hitting the nail on the head."
"In Brazil we maybe operated in that optimum, but most of the time we’re not optimising it," he commented. "But that’s like maybe once or twice we’ve done that this year.
"You look deeper into the detail to try and find any performance that’s left over," he added. "You chase it more than you’ve ever done before. You’re really hard on the guys: ‘Close the damn car up!’
"Those are things that I’ve been applying more energy towards and being a lot harder with the team on. Because we need every millisecond we can get."
And Hamilton said that he still "lived in fear" of contacting COVID again as he did at the end of 2020 - thankfully after the title had already been sealed.
"Everyone I see around me, all my friends, if they miss a day of work, or a week of work, it’s not the year over. Whereas it’s critical for us drivers. The year can be over if you miss one or two races.
“I would say the biggest part of the pressure of the season has been the pandemic," he said. "It’s been quite tough… I would say harder to find a balance in normal life, in and around your work life.
“In some places they are relaxing the rules, and then it’s so easy to let your guard down and find yourself in trouble," he added. "So you keep your distance from everyone, hold your breath around everyone.
"It’s definitely, I would say, much, much harder."
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Lewis Hamilton, Mercedes