The two combined to help McLaren seal fourth in the Constructors', following an impressive second half of the season, in which the MCL60 proved the second-fastest car behind Red Bull.
Piastri claimed victory in the Qatar Sprint race, while after the summer break, Norris took four second-place finishes to Max Verstappen, but there were costly mistakes, especially in qualifying from the British driver.
He lost out on probable pole positions in both Qatar races due to exceeding track limits, while a lairy moment in qualifying for the Abu Dhabi Grand Prix cost him a front-row slot, and a potential chance of finishing fourth in the Drivers'.
Piastri claimed wide-spread praise for his rookie season, claiming 97 points and two podiums, with Stella believing the high-performance level of both could lead to mistakes.
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Stella open to driver theory
"It is two questions, and the first one I can answer with 100% certainty," Stella told media including RacingNews365 when asked if the performance of both drivers was spurring each other on, and potentially leading to mistakes.
"We have two quick drivers and the two of them elevate their game, like when you look at the overlap between the two in practice sessions, we can already see that if we don't look so competitive in the times, if you put together the best of the two, we are actually strong.
"For instance, [in Abu Dhabi], Oscar had a couple of places where he needed to work and adapt, and the same for Lando, he had one place where he needed to work and adapt based on looking at each other's data.
"So because you have a competitive team-mate, you can see how you can go quicker in some places, and this is what happened.
"The second element is a little more difficult to assess.
"But we need to make sure that we support our drivers to extract the potential, which is something that is just continuous improvement, and you have to use all the information, including looking at trends during qualifying.
"What happens at the point we make a mistake, under what circumstances did we do that?
"Is there something that can be improved from the human side?
"So we definitely know that when the team-mate is strong, the second element tends to be more prevalent."
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