Piastri finished fourth in the British Grand Prix, a race won by Lewis Hamilton and one arguably thrown away by McLaren.
Lando Norris had led ahead of the opening round of stops, followed by his McLaren team-mate, the pair having passed the two Mercedes and Max Verstappen as rain began to fall.
The decisive moment for Piastri came on Lap 27, when the call was made to pit Norris.
At the time, the McLaren duo were separated by little more than six-tenths, with a small gap back to Lewis Hamilton and George Russell in third and fourth respectively.
It created a scenario where Piastri was guaranteed to lose time whatever call was made, the team opting to leave him on track for another lap instead of stacking him behind Norris in pit lane.
“To be honest, that decision in the race is probably the hardest call you’re ever going to have in motor racing,” Piastri said of the call.
“You’ve got two cars, one-two, separated by half a second with rain coming down. I don’t think it gets any harder than that.
“Clearly some things we need to review. I think double stacking would have been the better call, but hindsight’s a wonderful thing.
“We just need to see if we had any information that told us that was going to be a better choice, but yeah, obviously a little bit painful given the gap to Lewis.
“I knew if I got in front then it would be my priority as we go into the pits,” he added in regards to why he didn’t take it upon himself to open a gap to Norris to facilitate a double-stack.
“That’s why I say it’s one of the hardest decisions, because I’m trying to get the lead, give myself a priority, the team don’t know which car is going to come in first to the pits. Yeah, it’s just incredibly tough.”
By remaining on track, Piastri haemorrhaged time as conditions deteriorated.
In normal conditions, the Australian would have pitted at the end of the following lap with a near 20-second delta to Norris.
As it panned out, he held less than a three-second advantage when he peeled into the lane; he lost the better part of an entire pit stop in a single lap.
“The last couple of corners were very, very tough,” Piastri admitted when asked how quickly he realised staying out was the wrong choice.
“I could see on my dash that Lando was like five seconds behind me when I pitted, so I knew I was in a lot of trouble then.
“But yeah, I knew it was the wrong call basically instantly.
“Obviously frustrated at that point, but I knew that there was rain still coming,” he continued.
“After the first couple of laps I could see that the cars ahead had clearly used up their inters a lot in the first couple of laps, so I was actually optimistic at that point, but then I kind of hit the same wall as everyone else.
“But I knew we would have more chances later in the race with getting back onto the slicks, the choice of tyres we had, so I knew there would be more opportunities,
“I just tried to give ourselves the best chance of still trying to win.”
Had Piastri followed Norris into the lane and queued behind his team-mate he’d likely have lost out to Hamilton at least. However, he’d have likely emerged ahead of Russell as Mercedes pulled both its cars in on Lap 27.
Instead, he fell to sixth, with Max Verstappen rising to third after he pitted a lap earlier than the leading group – and two laps earlier than Piastri.
“I think we just need to review if we put enough weight on that decision,” the Australian noted of the decision not to double-stack.
“Obviously when the two cars are so close like that, you lose a lot of time doing a double stack.
“The conditions were getting trickier, but it was very, very hard to judge. It was only really half of the track that was really difficult until the lap that I stayed out, and then the whole track became difficult.
“Just very, very difficult for everybody involved, but yes, I think in hindsight double stacking would have given us a very good chance of winning.”
Though he dropped back to sixth, Piastri didn’t give up hope and a late charge saw him improve to fourth – aided by Russell’s retirement.
In the final stint, he opted for a new set of medium tyres for what was a 15 lap run to the chequered flag.
Norris opted for soft tyres, a decision which likely cost him a chance of victory, as did Hamilton who claimed the lead after the Brit slid long in the pit box, delaying his stop.
The medium rubber left Piastri the fastest car on track in the closing laps (though a late stop for Carlos Sainz saw the Ferrari driver take the point for fastest lap), taking the chequered flag only 4.8s behind Norris – and 12.4s back from the race winner.
“Every other decision we absolutely nailed in that race,” Piastri said of his strategy aside from his opening stop.
“I think me and Lando put ourselves in a great position getting to the lead.
“The decision on my side to put a medium on was the right call. I think we were the quickest at the end.
“It’s just a shame that we weren’t in a better position in the middle of the race.”
Piastri now sits fifth in the drivers’ championship with 124 points, while together with Norris has helped move McLaren to within seven points of Ferrari for second in the constructors’ title race.
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