Likely to go down as one of the great wet-weather races, due to standout performances from race winner Lewis Hamilton and especially third place driver Max Verstappen, the 2016 Brazilian Grand Prix hinged on great driver skill as well decision making from the pit wall.
Whilst it was not decisive at the top of the Drivers’ championship, it was a hugely significant race in the struggle for survival at the back of the grid. Sauber finally scored points, to lift them into 10th place, ahead of Manor in the Constructors’ championship, unlocking tens of millions in prize money.
So how tough was it to make the right calls on Sunday and did Red Bull, for all of Verstappen’s brilliance, mess it up on the strategy side?
The Art of Decision making in the rain
The weather in Sao Paulo was hot and sunny on Friday and it deteriorated through cooler conditions on Saturday to constant rain on Sunday. Most rain-affected F1 races tend to be changeable from wet to dry or the other way around. It’s quite unusual to have a constantly wet race.
Pirelli has two tyres available for these conditions; the extreme wet and the intermediate. The crucial thing about deciding which of these to use is the crossover point, when one of them is demonstrably faster than the other.
On Sunday we saw the intermediate tyre at one stage lapping 1.5s faster than the wet and that was enough to persuade several teams to take a chance. Often there will be a ramp up of pace, as the intermediate gets warmed up and then the delta grows to two seconds, then three then five and so on until the whole field is on intermediates. That did not happen on Sunday and many strategists say it was never going to because of the prevailing weather conditions.
But it’s not as simple as spotting a pace advantage on another car and putting your car onto the different tyre. Each car has different risk profiles, depending on track position and car pace. So the leaders, who do not have traffic and therefore as much spray to contend with, have a fast car and track position, do not need to take risks.
Cars outside the top ten points positions are in traffic, which means lots of spray, and they are not able to use any car pace advantage they may have and therefore the risk of rolling the dice with the other tyre is lower.
The major risk is that there is an accident, which is more likely on a wet track and that brings out a Safety Car and/or a red flag stoppage. Then all the strategies are neutralised as everyone gets a free choice of tyres for the restart and cars that pitted for the intermediate have lost all their track positions. That is exactly what happened on Sunday.
So taking all these risk factors into account, when the weather forecasts all say that there is no sign of significant improvement in the weather, as was the case throughout Sunday’s race, then it is a bit like a fast pit stop versus a steady pit stop.
The fast one gains some time but there is a danger of a mistake or unsafe release. A steady stop loses a fraction of time but there are no slip-ups. The intermediate vs wet weather choice at Interlagos was like that.
So the smart thing for a strategist outside the top six to do was hedge their bets and split the strategies, putting one car on the intermediate tyre and leaving the other one on the full wet.
In that way you’ll get it right with one and wrong with the other. For a team simply looking to score points that makes sense.
For a team like Red Bull that has its tail car out of position and lower down the order than expected (Daniel Ricciardo) it is also worth the gamble. But when Verstappen passed Rosberg for second place, it was extremely risky to then pit him for intermediates, putting him into traffic and putting all the team’s eggs in one basket, as we shall see.
Red Bull has split strategies to great effect in Spain and Malaysia this year, but strangely they did not do it in this race.
In a split strategy situation you need to put your lead car onto the strategy you think is most likely to come off. So at Sauber, for example, they desperately needed a point and they left their lead car (Nasr) on wet tyres while their tail car (Ericsson) went onto intermediates – and he crashed on them.
But as other cars went to intermediates, Nasr rose up through the positions and at one point was running as high as sixth place. At that stage the championship points predictor showed Sauber moving up to ninth in the constructors’ table. Toro Rosso did the same as Sauber and its lead car, Sainz, finished sixth. Both Renaults and both Williams did the same as Red Bull and got no points at all.
In all, 12 of the 22 drivers went for an intermediate tyre at some stage and all but two of them, Bottas and Magnussen, were forced to pull out of it.
Mercedes stuck to its guns and did not flinch when Red Bull twice tried to provoke it into stopping for intermediates. The Mercedes strategist did not feel the crossover numbers were compelling enough for the switch, he didn’t see the maths in it and also he had the most to lose from a bad call as his cars were leading the race. On top of that both drivers felt the wet tyre was the best option throughout.
We have seen in the past that some midfield teams follow what the benchmark team or driver does in this situation. Several teams scored good results in the 2010-12 period in wet/dry races by following what Jenson Button did in his McLaren. Button seemed to have an uncanny knack of feeling the grip and pitting one lap ahead of the crossover point from wet to intermediates. That gave him an advantage and won him races and it certainly boosted the results of those who followed him into the pits.
At Interlagos, Force India copied Mercedes and it brought Sergio Perez a fourth place and seventh for Nico Hulkenberg.
In reality though, a constant rain situation, such as was the case on Sunday, it’s not as simple as that; as there was nothing in the forecasts that suggested an easing of the rain, the numbers from the intermediate tyre performance were not enough. Strategists had to look away from the pit wall at the environment around them. One senior strategist told me he had a puddle he would check every few minutes to study the intensity of the raindrops splashing onto the surface; that told him the rain was at a fairly constant rate.
Red Bull’s decision with Verstappen was more based on the numbers and less on the environment and made little sense.
It cost him second place for sure, even if they believed that the gamble might bring them a win.
But the upside for the fans was that Verstappen’s recovery drive from 14th place was one of the highlights of the season.
The UBS Race Strategy Report is written by James Allen with input and data from several of the leading teams’ strategists and from Pirelli
RACE HISTORY AND TYRE USAGE CHARTS
Courtesy of Williams Martini Racing – Click to Enlarge
A graphic representation of the Race History in terms of the lap times of each car. It shows the relative pace of the cars and the gaps between them in the race. Upward curve is good pace, downward curve demonstrates slower pace. Sudden drop is a pit stop.
Look at the consistency of Lewis Hamilton’s pace through the race. That also demonstrates how consistent the conditions were. The spikes of pace from Ricciardo when he went to intermediates soon ebb as the rain does not abate and safety cars neutralise the strategies.