Strategy becomes a whole lot simpler when you have a faster car than your opponent. Red Bull demonstrated as much in the two Austria races, but in the preceding Paul Ricard race things were rather more nuanced. The Red Bull advantage was not as clear-cut and once Lewis Hamilton had taken the lead at Turn 1 after Max Verstappen ran wide, it looked like he had the race under control. The Red Bull was not sufficiently faster that Verstappen could overtake on track and as Hamilton steadily built up a lead of over 3sec during the first stint, it was difficult to see any strategic way for Red Bull to break Hamilton’s command.
But Mercedes underestimated just how big the undercut effect could be and mistakenly believed Hamilton’s 3.1sec advantage over Verstappen before the Red Bull pitted would be enough to allow Hamilton to pit a lap later and rejoin in front. It wasn’t.
Hamilton had used up more of the front tyres by the time he came to do his in-lap than had Verstappen. By keeping out of Hamilton’s turbulence zone Verstappen ensured he still had plenty of rubber by the end of the stint. Also, this is partly a function of the car’s balance and its general performance. As Bottas observed in Austria: “If you’re further off with the car you have to push harder and the tyres suffer.” So Verstappen’s in-lap was quick. Hamilton’s in-lap was 0.9sec slower. More important, Verstappen’s out-lap was very quick. The difference between that and Hamilton’s concurrent in-lap was the big reason for the undercut working.