As the wheels went up on Sunday evening on a Mercedes charter flight back to the UK, team engineers were still trying to figure out how, exactly, they had lost the French Grand Prix. Flying from an airstrip running directly parallel to the crater on Circuit Paul Ricard, the view from the jet window offered a complete picture of the defeat scene, yet the details were lost in the data.
The grassroots race a few hours earlier was so closely contested that a second of "lost" time at Lewis Hamilton's pit stop decided the result. Presumably Max Verstappen would have won regardless of the missing second given his Red Bull-called performance later in the race, but given that he was certain to win six miles from the end, Mercedes had unaccounted pits. Another time to stop might have made all the difference.
But we are getting ahead of ourselves. To fully explain the story behind missing time, we need to start from the beginning.
After qualifying on pole position, Verstappen lost the lead in the first corner when a tail wind surprised him with the brakes in Turn 1 and went deep into the corner. He left the top of Turn 2, allowing Hamilton to pass him and take the lead, and rejoined third-placed Hamilton's teammate Valtteri Bottas in second.
It could have been a decisive error in the race as it gifted Mercedes strategists the upper hand when it came to the first pit stop - Verstappen now needs to keep an eye on Bottas as well as Hamilton.
When Bottas was brought in to replace a tyre, the wall of Mercedes Pitt began to use his strong hand on lap 17. This put pressure on Red Bull to do the same with Bottas' fresh tyres, allowing him to lap faster than Verstappen on older tires - a strategic play known in F1 as an "undercut". As Mercedes had expected, Red Bull's strategists countered in a similar fashion, bringing Verstappen one lap later – at which point he was 3.2 seconds behind race leader Hamilton but still in a position where he could not race. Could have started again ahead of Bottas.
Because he held out a lap longer than Bottas, Vertspan lost 1.2s relative to the Finn on the undercut, but surprisingly at Red Bull, Mercedes did not drop Hamilton at the same time.
With the advantage of sight, it would have been right to bring Hamilton on lap 18 and it may have won Mercedes the race. If the two race leaders had pitched the same lap together and the tire changes on both cars had gone according to plan, both would have taken out the pits in the same order as they entered, ensuring that Hamilton took the lead at the start of the next stage. Controlled race and speed.
Of course, if Hamilton had pitched on lap 18, Verstappen would have seen that game in front of him and Red Bull could have opted to stay on track. But there would have been little strategic advantage in doing so as that would only have opened himself up to a more serious undercut for both Bottas and Hamilton, potentially leaving him in third place upon his return to the track.
Ultimately, it was a catch-22 situation for Red Bull.
So why didn't Mercedes pit Hamilton with Verstappen on lap 18?
Ultimately, Mercedes' strategy modeling software was telling the pit wall that, thanks to Hamilton's 3.2 lead over Verstappen, it could delay his pit stop until lap 19 and still emerge in front, even though What did Verstappen do? By staying out on lap 19, Mercedes could call in Verstappen to ensure Red Bull worked as expected on lap 18 and would then be able to call Hamilton a lap later and still hold the lead.
At least that's what the strategy model says...
"We thought, when we had just over three seconds for Max, that we were safe from the undercut, and that was not the case," said Andrew Shovlin, Mercedes' head of trackside engineering, on his flight home on Sunday. Waiting to board. evening.
"Even now, we don't fully understand why our models were telling us it would be fine, so clearly there's something we need to go out there and figure out.
"If we had put Lewis on lap after Valtteri - would Max have followed us, I don't know - but if we had done that, it would have put us in a good position.
"So actually we thought we were fine [to stay out until lap 19]. We couldn't go further down the road because Lewis fell flat in that first stint, but we could have put Lewis on lap one first . "
But Verstappen is the type of driver that rival strategists opt out of making, and their software models look silly.
While Bottas gained 1.2 seconds relative to Verstappen using the undercut between laps 17 and 18, Verstappen gained 1.6 seconds over Hamilton when comparing his split times as on laps 18 and lap 19.
It was a significant chunk of time for Hamilton to get out of the buffer, but that doesn't explain the full 3.2 Mercedes thought it was at hand.
When it came to Hamilton's own pit stop on lap 19, his steady time was actually 0.1s faster than Vertspan's, but his total time from entering the pit lane to the exit was 0.6s slower. This discrepancy between steady time and pit lane time was likely down to how late Hamilton was on the brake entering his pit box and how much wheelspin he had left it, but when Verstappen of 1.6 was found on the track, This still only accounts for 2.2 of the 3.2 gain Hamilton gained before Verstappen pitched in.
Clearly the remaining second disappeared somewhere as Verstappen reached the top of Turn 1 early on lap 20 ahead of Hamilton and took the lead.
"We still need to move on because we haven't understood how we lost the position," Shovlin said. "We only account for about 2.5 out of 3.0, so that's something we need to look at in detail, how we were so far less than we expected."
This explains why the team's chief strategist, James Wowles, went on pit-to-car radio after the race to tell Hamilton: "He was on us".
Speaking to the media after the race, team principal Toto Wolff also admitted the mistake.
"Our car performance was good, I think we probably had a faster car," he said. "We [first] lost the race at the pit stop, thinking we had enough protection against the undercut, which we didn't.
"We had a solid three seconds to save from the undercut and it wasn't quite as much as it looks and from there we were really on the back foot."
Once Vertsepen took the lead, he was able to control the race - but it required some top-class driving and some bold calls from the Red Bull pit wall to secure the win.
In an attempt to gain the lead on the track, Hamilton pushed Verstappen hard after the first pit stop, killing both cars' tyres. As more and more radio calls from drivers expressed concern, especially over the condition of the front left tyres, it became clear that the two-stop strategy might be the quickest way to the checkered flag.
A similar situation happened at the Spanish Grand Prix earlier this year when Verstappen was leading the race and Hamilton made a pit stop from second to pick up new tires and hunted Red Bull to take the win.
That option was also available to Mercedes in France, but the main difference was the presence of fourth-placed Sergio Pérez. Perez ran the race longer on his original set of Piralis than the top three drivers and so had relatively fresh tyres, even after Hamilton and Verstappen began to consider a second stop.
Perez's position at the back of the top three meant that Mercedes drivers would have to overtake him if they wanted to take a shot at the second pit stop, and the relative youth of Perez's tyres meant it would be difficult.
"The fight between the three cars was intense up front and I think you basically had to choose to continue with a stop or two," Wolff said. "Half two was a threat to us because Perez was on the way, and we went wrong today."
For Verstappen, of course, there were no such concerns as Perez would be asked to go out of his way, making it possible for Verstappen to make a second pit stop, drop to fourth and hunt down Hamilton before the end of the race. Gone. .
"At the time it felt like Mercedes were pushing too hard, and we just didn't want to be in the same position as Barcelona," Red Bull team boss Christian Horner said after the race.
"It's always a difficult task to pit from the lead with 21 laps, but that's what we did, while meanwhile leaving Checo at a stop, and it worked.
"Obviously Max had the speed to catch and pass the three cars ahead - it was important to pass Bottas quickly - and then it was great to get Lewis [for the lead].
"It was a bit payback for Barcelona at the start of the year and a half to go."
It was clear that victory meant something terrible for Verstappen and Red Bull.
"I think we came here knowing that this will be one of Mercedes' stronger circuits," Horner said.
"I mean, he's led every lap here before this race bar one, and I think it was all with Lewis.
"So it's fantastic that we scored a big one here this weekend, and Max should have won two weeks ago [in Baku].
"But you can see how close it is, there is nothing between the two cars.
"So we just have to keep pushing, keep looking for performance, and by all means keep going.
"There's such a long way to go in this championship, we can't take anything lightly."
To add to Red Bull's satisfaction, the defeat hurt even more for Mercedes as it was in a winning position before the first pit stop.
"It's annoying because I think we could have won the race and had two cars on the podium and we are in a championship where we can't let go of these opportunities like today," Shovlin said.
"But at the time they came they weren't easy decisions and basically we've got a good race car - we're a bit lacking in qualification - but in a normal race we can put them under pressure.
"But this team can beat Red Bull at their best. We saw that the opportunities missed were the difference.
"We know it's going to be difficult and we think they are the favourites, they obviously have a great package, but if we do our best we can beat them and win the championship."