Why did it go so wrong for Ferrari in qualifying?

Everything was looking pretty good for Ferrari after final practice for the Spanish Grand Prix.

Sebastian Vettel was third fastest, within a tenth and a half of Nico Rosberg's Mercedes and just 0.021 seconds adrift of Lewis Hamilton's.

Then came qualifying.

Ferrari was nowhere around Barcelona's Catalunya circuit, struggling for speed through each phase of the session and ending up on the third row - behind both Red Bulls as well as the two Mercedes.

The gaps were enormous too. Hamilton's pole lap in Q3 was over a second faster than Kimi Raikkonen's best effort for the Scuderia; Daniel Ricciardo's Red Bull almost half a second clear.

Four-time world champion Sebastian Vettel was two tenths further back than Raikkonen.

For a team that has been clearly the second fastest over the first four races of this Formula 1 season, and had looked potentially capable of challenging Mercedes at Barcelona, this was a disastrous result.

Ferrari could not offer a clear explanation for this following the session.

Vettel suggested the car behaviour changed suddenly in qualifying, compared to how his SF16-H had felt earlier in the weekend, and reckoned he was struggling for grip "overall" rather than through any specific part of the circuit.

Raikkonen pointed out that Ferrari did improve overall between Saturday morning and qualifying. In fact he ultimately bettered his final practice time by almost a second through the three stages of qualifying.

Vettel fared much worse, ending up over a tenth adrift of his practice three best after Q3.

He was the real anomaly among the top 10 - the only driver who failed to go quicker than he did in final practice. The rest all found somewhere between 0.5 and 1.2 seconds.

Raikkonen's improvement looked fairly normal, but he trailed both Red Bulls by several tenths after third practice, which has to count as an underperformance given where Ferrari usually stands.

So what went wrong in qualifying?

A TYRE ERROR?

The most likely explanation is that it had something to do with the way Ferrari used the Pirelli tyres - perhaps a mistake on tyre pressures or a problem with the temperatures of the blankets?

This is a problem Hamilton encountered when he trailed Rosberg in qualifying here last year.

But according to sources at Pirelli there was no obvious error made by Ferrari in this case.

In fact Ferrari struggled relative to Mercedes and Red Bull throughout the session, so if it had made an error in terms of the way it prepared its tyres it would have made that error repeatedly, and it would surely have been obvious to the engineers.

A BAD SET-UP?

It's more likely that Ferrari misread how to adapt to the change in track conditions between final practice and qualifying.

The air and track temperatures climbed substantially, which will always have a knock-on effect on how the sensitive Pirelli rubber behaves.

Add in the fact that the soft compound has not been used at this track before - except in the much cooler conditions of winter testing - and it wouldn't take much to knock a perfectly well-balanced car off kilter with tyres that are not working within their correct temperature range.

If you don't get the Pirellis prepared properly you simply slide around throughout the lap and go slowly. This is what happened to Mercedes in Singapore last season.

We don't know whether the Ferrari overheated or underheated its tyres, but both Vettel and Raikkonen lost several tenths to the Mercedes drivers through sector one of their fastest laps.

This sector only includes Turns 1, 2 and 3, so Ferrari was probably in trouble immediately, rather than finding it gradually as the lap progressed.

The surprise is that Ferrari has generally looked better on softer compound tyres in hotter weather over the past couple of seasons, so one might anecdotally expect these conditions to play to its strengths.

Perhaps Ferrari doesn't yet understand the nuances of the Pirelli tyres in particular circumstances as comprehensively as others.

ARE THE DRIVERS TO BLAME?

Many drivers spoke about the challenge of keeping the soft tyres alive for an entire flying lap on this track.

Take too much from them in sectors one and two and you have nothing left for sector three.

However, for drivers of cars with more downforce - i.e. those at the front of the grid - this should be less of a problem.

It is generally much easier for a Vettel or a Raikkonen to keep their tyres in good shape through the faster turns in the early part of a lap of the Catalunya circuit - in readiness for the rear-tyre punishing demands of all those low-speed acceleration zones in sector three - than it is for say the Sauber or Manor drivers.

Both Ferrari drivers are world champions, and obviously very capable, but it's possible that both were caught out by the conditions and either couldn't or failed to adapt quickly enough.

There was quite a wide variation in how much time individual drivers in the top 10 found between Q2 and Q3.

LAPTIME GAIN FROM Q2 TO Q3
1. Ricciardo 0.950s
2. Sainz 0.634s
3. Bottas 0.501s
4. Rosberg 0.479s
5. Raikkonen 0.393s
6. Vettel 0.354s
7. Perez 0.221s
8. Alonso 0.211s
9. Hamilton 0.159s
10. Verstappen 0.091s

The large variations would suggest the track was difficult to read, or perhaps that individual drivers could find lots of laptime from making particular adjustments to their technique.

Ricciardo made a much larger step than Verstappen for example, and they were driving essentially the same car.

However, the Ferrari drivers both found similar amounts of time, which suggests they were both suffering similar problems during their flying laps, and that suggests the car is more likely to blame.

SO WHAT DID FERRARI DO WRONG?

Ultimately it will almost certainly come down to a combination of several variables.

Ferrari probably doesn't understand how the soft Pirelli rubber reacts to changes in track conditions quite as well as some others on the grid.

This potentially led it to make set-up changes that didn't work quite as well for getting the most out of what remain incredibly sensitive and difficult tyres to operate correctly - on a circuit where the limitation changes from the front to the rear between the start and the end of the lap.

This likely then created a car balance that was difficult to deal with for its drivers, which meant they struggled to keep their tyres from sliding too much, which meant their grip problems increased exponentially throughout their laps and caused them to haemorrhage laptime to their main rivals.

It's what Manor's Pascal Wehrlein called "the devil's circle", and it's one that seemed to trap Ferrari unexpectedly at Barcelona.