Carlos Sainz says Ferrari has lost "two or three months" of Formula 1 car development after reverting to its Imola specification for the British Grand Prix.
Ferrari's previous upgrades in Barcelona, which included a revamped floor, exacerbated the SF-24's bouncing issues through high-speed corners as Sainz and Charles Leclerc struggled for performance and comfort in Spain and Austria.
That led to experiments in Friday practice at Silverstone, with Sainz and Leclerc splitting packages to perform a back-to-back test and get on top of the issue.
In the end Ferrari decided it was better off rolling back the car to its Imola-spec, which has made the car more driveable through Silverstone's high-speed swoops like Maggots and Becketts.
But by racing with the same car it did in May, that also means Ferrari has left a lot of performance on the table compared to Red Bull, Mercedes and McLaren, who did successfully upgrade their machines in recent months to varying degrees.
In Sunday's mixed weather British Grand Prix, the gaping performance gap with the frontrunners was clear to see as Sainz finished fifth, 47 seconds adrift of Mercedes's winner Lewis Hamilton and 35 seconds behind the car ahead, McLaren's Oscar Piastri.
"It is clearly not good enough," Sainz acknowledged. "We have basically the same car as in Imola and since Imola everyone has upgraded, probably added two tenths to the car and we have had to revert.
"We have lost two or three months of performance gain in the wind tunnel or performance we could have added in these three months, so clearly we haven't taken the right calls recently.
"I feel like today was at least back-to-basics, back to a car which was in Imola and we just need to upgrade it from here. But it is clear that our rivals are a good step ahead of us."
In contrast to team-mate Leclerc, who paid the price for an early switch to intermediates on a track that was still too dry and finished a lapped 14th, Sainz and his team made all the right strategy calls as two different showers affected the running, but in all conditions his Ferrari lacked the pace to keep up.
"I think we did the maximum," he added. "Especially in the middle of the race when it was slicks-on-wet, I managed to catch the podium positions by six or seven seconds in those conditions that I always enjoy.
"Honestly, all the calls were pretty much spot on, all the tyres, all the radio calls. It was just a shame we were not faster because I feel like we would have been 100% in the fight for the podium or the win.
"But [fifth] and a bonus point at the end with the fastest lap, so we need to be happy."
With two more races to go until the summer shutdown, Ferrari might have to keep going back and forth on its specifications at Budapest's twisty and extreme high-downforce Hungaroring, and the much faster Spa-Francorchamps.
Sainz was adamant that his car would be "undriveable" in Spa with the new floor, but Ferrari might get away using the latest version on the lower-speed Hungary track.
"We will bounce in Turns 4 and 11 [in Hungary], but until something better comes we may have to live with bouncing for a while," he explained.
"In high-speed tracks we might have to run the floor of this [older] package because if not, the other one is undriveable.
"I trust the team will make the right calls circuit-to-circuit until a more solid package, which is not bouncing in high-speed and good in low-speed, arrives and then we will start thinking about battling the top three teams again."
