At McLaren's 2023 launch, even before a wheel was turned, the team realised it was in for a rough start to the new season because it found it had missed its aero targets.
Last week's three-day Bahrain test has gone reasonably well, but it also confirmed the team's expectation that just like last year it would start 2023 with a car that is too inefficient, and therefore generates excessive drag for a given downforce level.
Succeeding a 2021 car that was actually known for its excellent straightline speed, the 2022 MCL36 was known to be rather draggy, which forced the team to make trade-offs between top speed and optimum downforce levels.
It led to aerodynamic efficiency to be one of the priorities to address for this year, but soon after putting together the launch spec of the new MCL60 McLaren realised it had gone in the wrong direction and left a lot of performance on the table.
It will have now to wait until its first major upgrade package can be put on the car - which is planned for the Baku round at the end of April - to catch up.
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Stella, who has replaced the departed Andreas Seidl as team principal, says there isn't one reason why McLaren has struggled with efficiency for two years in a row, but that it ties in with the overhaul of the Woking headquarters' infrastructure.
"I wouldn't say there's a specific deficit in some areas, it's various reasons," Stella explained.
"We keep mentioning the technology, the lack of the wind tunnel. We keep mentioning that from a workforce point of view, we do have to expand the aerodynamic group, we went through a phase of contraction, we have now changed this tendency.
"If you see some top teams, if you see Red Bull, they have kept developing, they have expertise for a long time. And now they are in condition to respond to changes or regulations, improving year by year.
"I'm afraid that just continuous improvement and growth [is needed], and we have to improve in all areas."
Stella does not want to use F1's cost cap as an excuse for why McLaren hasn't come out of the 2022 rules reset as well as it would have liked, nor is the MCL60's inefficiency linked to the subsequent 2023 floor tweaks.
"I wouldn't say the budget gap is necessarily a limitation for us," he said.
"It's an excuse that I don't want to invoke because McLaren is now in a situation in which we do have resources that we can invest, these investments have already started, we have been able to optimise within the cost cap.
"It takes time to achieve the standards required from a technological point of view, from an expertise point of view, from a number of people point of view, to compete at the top in Formula 1.
"It is not an effect of changes in regulations. We didn't take a step backwards. We just didn't develop fast enough."
