Stella took over last winter to replace Andreas Seidl, who departed to head up Audi's 2026 entry with Sauber.
One of his biggest early decisions was to restructure the technical departments, creating three clear pillars with their own responsibilities.
While two of the three technical directors are still on gardening leave after signing from rival teams, Stella thinks the new structure has empowered the technical talent at the team and created "clarity on the responsibilities".
He singled out the rejigged aero department led by Peter Prodromou as an "essential" move that allowed McLaren to unleash a barrage of mid-season upgrades that turned its 2023 season around as it beat Aston Martin to fourth in the constructors' standings.
"The technical restructuring was a fundamental enabler," Stella said when asked by Motorsport.com how much of McLaren's progress would have been possible without it.
"The restructuring itself includes people that actually haven't started yet.
"If we talk about the new technical configuration, which includes three technical directors, two of them haven't started yet. It was Peter Prodromou in charge of aero, David Sanchez in charge of performance and concepts, Rob Marshall in charge of engineering and design.
"Effectively, this structure has given clarity on the responsibilities and has allowed also - and it was essential in the short term - to restructure the aerodynamic department, putting Peter Prodromou in charge, supporting Giuseppe Pesce, these guys have been absolutely instrumental in setting the new direction for the design of the car from an aerodynamic point of view."
Both Marshall, who joins from Red Bull, and Ferrari signing David Sanchez will join the team in January after their gardening leave finishes, as part of over a dozen technical hires that McLaren has made to bolster its ranks.
But Stella is key to stress that the nine podiums Lando Norris and Oscar Piastri scored in the second half of the year, as well as rookie Piastri's sprint win in Qatar, are the result of the people who were already in place at Woking.
Similarly, its new wind tunnel, which came online in the summer, has only been used on the 2024 car project.
"This has been the enabler to use the talent that was already available at McLaren, because the people that physically design the geometries are the same people," he explained.
"But unleashing their talent by giving clear direction, making clear objectives, and also trying to make sure that empowerment and enthusiasm are the foundation of how we deal with people. This has been instrumental. And that's also how we are trying to get into the future."
