McLaren went into the inaugural race weekend around the streets of Vegas with muted expectations, but while similar pessimism proved unwarranted in Austin, Mexico or Brazil, it did turn out to be justified on the low-downforce street circuit.
Lando Norris was knocked out by former team-mate Daniel Ricciardo by a mere 0.020s in Q1 to qualify 16th, while Oscar Piastri followed in 19th in what has been McLaren's worst qualifying performance since it upgraded its MCL60 in the summer.
But while McLaren's specific weaknesses in low-downforce and low-speed corners played their part in its double Q1 exit, Stella explained that the team's main stumbling block was the execution of the session itself.
"The fact that we were not performing very well left us on the back foot because we were very focused on trying to squeeze some performance out of the car," Stella explained.
"There were quite a lot of changes from yesterday, which finally actually added some performance.
"But we haven't done enough work because we're being on the back foot in understanding how you should actually use the tyres for qualifying."
Both Norris and Piastri opted to only use one set of soft tyres compared to two sets for their competitors, based on evidence from final free practice that Pirelli's soft compound could last for three qualifying laps before degrading.
"In FP3, we saw with Oscar that actually the third lap was faster and he was on a fourth lap in which he was as fast as the third," he added.
"So, we convinced ourselves that the tyres could have repeated the lap time and that was the plan into Q1.
"We were considering also to pit for a second set, but the drivers were both happy that the tyres were in a good condition and therefore we could have stayed on the same set.
"At the time we opened the third lap, we realised that the tyres were going off, but then it was too late to pit.
"So, the main reason why we are knocked out in Q1 definitely is not car performance, because thanks to the work done overnight, the performance has improved.
"But the choices in terms of how to use the tyres in Q1 and the execution of the plan wasn't ideal."
Piastri added that McLaren didn't have a clear indication that using a second set of softs would be the way to go because it also hadn't experienced as much graining as it did in Q1.
"I think in hindsight maybe using one set of tyres wasn't the right decision," he added.
"But from practice, and even during the session, there was nothing to really indicate that putting a second set on was going to be the best way forward."
"We damaged the tyres quite a lot, which we didn't really see in practice earlier either. The car was honestly not bad. I think if we had gotten through, we had the potential to be in Q3 and perform decently.
"I don't think the car is a complete disaster, it's just that the circumstances didn't really work out for us."
