The 2022 rules cycle has been dominated by Max Verstappen and Red Bull, but behind them teams have gradually closed up, with 2023 one of the most competitive seasons in history in terms the lap time differences between all 10 teams.
Heading into the third year of stable regulations, Stella believes teams will start encountering "diminishing returns" on aero development after two years of spectacular progress up and down the grid.
"I think this year, we will see that adding lap time will start to have some diminishing return, I would say, for the first time with this new regulations," Stella said.
"For two years we have seen progress, especially aerodynamic development, being quite steep. But now, I would anticipate that towards the end of the season, it will become harder for designers to be able to keep a very steep development rate.
"This is why as I said before, that we can be competitive if we are able to keep the development rate that we have experienced over the last 12 months."
McLaren finished fourth in 2023 after a remarkable mid-season turnaround, but with most teams now fully on board with a Red Bull-style design philosophy, Stella expects the gaps between teams will continue to decrease and similar jumps will be harder to make.
Alongside F1 development turning into a game of "millimetres", Stella hopes F1's budget cap and aerodynamic testing restrictions, that limit development time based on the constructors' championship, will do the rest.
"Over time, hopefully, we will see in the interest of the sport that the budget cap will start having an effect in terms of level playing field," he explained. "And also the aerodynamic restrictions, because we have to remember that cars that win or do well, from a championship point of view, have less aerodynamic testing available.
"So, hopefully, these regulations will allow this level playing field to be generated. And this will make the sport more enjoyable and more competitive in terms of results."
