Mercedes are usually accustomed to having composed and productive pre-season tests, relentlessly pounding out lap after lap and, usually, producing a frighteningly fast overall time by the end.
However, 2021 showed none of the usual Merc composure as the team seemed to struggle to catch up after a gearbox issue on the first day put them on the back foot.
Lewis Hamilton and Valtteri Bottas both seemed to struggle to control the rear of the W12, with the car having a twitchy rear as the drivers applied the throttle.
Hamilton, in particular, had an uncharacteristic few days as he flew off the track and spun on more than one occasion.
"It was pretty evident from the footage that the car was handling poorly and, conversely, the Red Bull in fact looked what we would call planted, but it was a very stable car especially through the last sector of the lap," explained James Vowles.
I think that's a fair observation, it was visible to the outside and I would say the lap times mirrored that as well. But it's also fair to say that we don't have answers as we are sat here now, so soon after the end of the test.
"[There's] huge amounts of data available to us and now a long journey ahead to try and understand what was causing that."
Mercedes' new-found issues appear to be closely related to the rule changes for 2021, which specifically set out to reduce the aerodynamic downforce at the rear of the new cars.
Mercedes' Andrew Shovlin says some of their problems were exacerbated by the specific track conditions, with gusty winds and an abrasive track surface at the Bahrain venue.
"The wind made it tricky," explained Shovlin. "When the wind is behind the car, you lose a lot of downforce because, effectively, the air speed is reduced. So some corners where the wind was behind, it was prone to doing that and then also the tyres are quite easy to overheat on that circuit and if you start sliding, you tend to lose grip and it gets worse.
So, there are a few problems."
Work is now full steam ahead back at base in Brackley, where Shovlin says Mercedes are concentrating on understanding the rear of their car before the season starts next week.
"Importantly, we could see that some of our competitors weren't struggling in the same way as us, so we need to put quite a focus on understanding why the rear end was a bit weak," he said.
"How we can get it more stable and predictable and that work is going on now, hopefully when we get to the race weekend it won't be so difficult for the drivers because they were having to work pretty hard to do the lap times that they were doing."