McLaren's Norris took pole for the Brazilian Grand Prix's sprint and finished second behind Red Bull's Max Verstappen, and that result repeated itself in Sunday's Grand Prix after Norris jumped from sixth on the grid to second in Turn 1.
But as rival teams faded and finished over 30 seconds behind the dominant Verstappen, who took a record 17th win of the campaign, Norris was the only driver able to stay close to the Dutchman, finishing just eight seconds behind after matching the Red Bull's lap times for large spells of the race.
PLUS: The crucial lap that swung F1's Brazilian GP from Norris to Verstappen
But as the high degradation race progressed, Norris could clearly be seen sliding backwards throughout his stints, explaining that "I'm not far behind for the first 10-15 laps in but that final phase, I just drop off a bit too much."
Team boss Stella acknowledged that amid McLaren's impressive developments this season, which has turned into the most consistent challenger of Red Bull in recent months, tyre management is the one area that still sets Red Bull apart.
"I think the difference is mainly in terms of lap time on used tyres," the Italian explained. "We have seen that in new tyres, we can fight for position.
"But as soon as the tyres degrade, then it would appear like Max, Red Bull, they can just have less degradation. The tyres were degrading maybe one-tenth every two laps.
"It's a significant amount of degradation and if you can limit that, after 10 laps in a stint, this is tenths of a second, so I think that's where they are superior at the moment."
The team has come on leaps and bounds in 2023 with its various upgrades, which have also helped with tyre wear, but it will need to wait for the 2024 car to make the biggest gains on that front.
"Where we think the difference is made, we can't do very much with this car," Stella added.
"The car has improved with the Singapore upgrade in terms of tyre management, but not enough to be able to compete, especially when degradation is high. And we saw some other cars degrading quite a lot, like Mercedes, Ferrari."
Stella said he was surprised at the extent Ferrari and especially Mercedes struggled to keep tyre degradation under control in Sao Paulo, with Lewis Hamilton sliding back to eighth and George Russell on the verge of dropping out of the points altogether before his retirement.
"That's a bit of a surprise, because normally, when you have this high level of degradation is also when Mercedes actually seems to do well," he said.
"We are not sure why that happened. And even from a Ferrari point of view, I would have expected Ferrari to be more competitive."
