McLaren is one of the teams that have progressed the most since the start of last year, with most of its gains coming from mid-2023 upgrade packages that allowed it to finish the season in fourth place.
The Woking team started 2024 roughly where it finished, battling Mercedes for third, although Ferrari's massive race pace improvements are keeping the Scuderia out of reach.
Max Verstappen's rare retirement in Australia allowed Lando Norris to claim the team's first podium of the campaign, followed in fourth by team-mate Oscar Piastri.
McLaren's 2024 challenger, the MCL38, has carried over the main weaknesses of its predecessor, with the team aiming to introduce a first upgrade package around the Miami or Imola rounds in May.
But team principal Stella cautioned that fully addressing its weak spots, including long-corner performance and a lack of DRS efficiency, which hurts top speeds, will likely take another 12 months of development.
"We are extremely happy with the rate of development over the last 12 months, but there's, I would say, another 12 months' development that we need to go through to actually offer a car that is strong in DRS and is strong in the long corners," he explained.
"Around race six or seven we should have a decent round of upgrades, and hopefully there will be potentially a couple of them throughout the season.
"It will take the whole season to actually add enough performance and say we don't see these weaknesses anymore because these areas have improved."
Stella doesn't think McLaren not getting rid of its weaknesses points to anything "going wrong" at the factory, nor is it unexpected. But he explained it is a result of the time it takes to develop and add performance in all areas, with teams having to pick and choose their projects carefully under the budget cap.
"Erasing the weaknesses is car development," he said. "It's not like you have these weaknesses because something goes wrong.
"There's nothing going wrong, the car is not developed enough and these aspects expose themselves, like you become weak in long corners or you don't have enough speed in DRS.
"But this is effectively a consequence of the development. If you ask me how is the car behaving, I say very well, like it goes as expected.
"It does exactly what we expect from the wind tunnel. It does what we expect from the computer development."
