Several years ago, McLaren operated a three-person technical structure with Tim Goss, Matt Morris and Peter Prodromou working alongside each other.
Goss and Morris later left the team, and in 2019 James Key joined as technical director with overall responsibility for the car.
The latest structure has derived from a review commissioned by CEO Zak Brown and conducted by Stella over the latest winter break, after the latter replaced Andreas Seidl as team principal.
As a result, Key left the team and a new structure was been installed, with three technical directors working together, namely Prodromou (aerodynamics), former Ferrari man Davide Sanchez (car concept and performance) and Neil Houldey (engineering and design).
Stella insists that the current arrangement cannot be compared with the earlier version.
"I think the only common thing in that organisation and this one is the number three," he said.
"The rest is completely different. At the time, which is when I joined McLaren in 2015, there were three technical directors. I think the separation of competencies was very confusing.
"Even for internal people, it was quite difficult to understand who was doing what. And the first difference is that now we know exactly what the criteria are for this separation.
"In the structure that we have deployed, we want to have clear leadership in relation to the three fundamental areas to make quick cars in modern F1, which are aerodynamics, car concept and engineering.
Source: Autosport