Piastri's stellar junior series credentials and the tug-of-war between McLaren and Alpine over his services made his debut one of the most highly-anticipated rookie campaigns in years.
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A low-key start to 2023 for McLaren prevented Piastri or Lando Norris from grabbing headlines, but the unflappable Australian soon delivered on his promise by pushing his more experienced team-mate in qualifying.
A spate of mid-season car upgrades then enabled the pair to fight for podiums rather than low points finishes and, while Norris took seven of McLaren's nine podiums and scored double the amount of points, Piastri also impressed with a win from pole in Qatar's sprint race as well as grand prix podiums in Japan and Qatar.
While McLaren had high hopes for Piastri, team principal Stella admitted the 22-year-old delivered "beyond our expectations", impressing with how quickly he soaked up information.
"Our analysis is that Oscar's season has just been exceptional, and when I say exceptional I mean beyond our expectations," Stella said.
"It's the rapidity with which he learns that I think makes him exceptional. And this has been true in whatever scale you take, within the timeframe of a race, within the timeframe of an event, within the timeframe of the season.
"His gradient is so impressive, which obviously creates expectations for next season. And expectations require work to be confirmed. But the other good thing with Oscar is that he's such a grounded person, he's so committed.
"And if anything, working with him will be more about what we need to do to confirm this gradient, work that effectively has already started in terms of planning ahead onto the winter."
Piastri's exceptionally calm and mature nature for his 22 years has made a big impression on the entire paddock, and according to Stella, it is one of the key attributes behind his rapid ascent.
"Maybe one of the key enablers why he can grow so rapidly, is just the man beyond the driver," he explained. "He's so calm, he's so good at keeping himself in a status in which he can use the best of his talent.
"I don't have that quality. I have to think about my psychology to actively keep myself in the most productive state. For Oscar, this seems to come quite naturally or maybe he worked throughout his young career on that, I don't know, but certainly, it is remarkable.
"And even when I've seen great drivers, currently or in the past, all of them sort of sometimes underperform because they don't stay in the status in which they give their best. I think for Oscar, this is quite natural."
