Vettel could only manage 18th in the wet Q1 session, while his team-mate Lance Stroll was 20th and last.
The disappointing result for the local team came two weeks after Vettel and Stroll finished 17th and 18th in Montreal.
However, while it was clear at the time that the team had problems with tire temperatures after the pressure was calculated, this was not the case at Silverstone.
Instead, the problem was a simple lack of pace in the wet after limited track time with the latest update package.
“It just seemed like we weren’t fast enough,” Vettel said.
“We lost a lot of time. And I guess everywhere in the lap, I mean balance-wise, I had a lot of understeer in the car and I was waiting for the car to turn.
“But I don’t think that’s the main thing. For some reason, I think we weren’t able to create the grip we should have.
“And then you don’t spin the car, and then your view of the road grip isn’t great. That’s why everything happens somehow late. And one thing adds to the other, so not really.”
Sebastian Vettel, Aston Martin
Photo: Zak Mauger / Images of motor sports
Vettel, who started the first quarter with an extra pit stop to change his helmet after a visor problem, said it was difficult to make a judgment about the upgrade package.
“I think it’s hard to say because this morning I think the car felt fine in terms of balance,” he explained.
“But I think Silverstone is a very fair track in terms of where you are and we’ll see on Sunday what the pace is in the race.
“I don’t think we can judge the upgrades yet, but it certainly wasn’t a quick and massive move all at once. So there are still some things we need to understand.”
Regarding the race, he added: “We have to be realistic. We just didn’t seem to be very competitive this weekend.
So scoring points will be difficult, but that should be the goal. So we’ll see. Maybe this time the security machine is working in our favor. I don’t know.”
At the same time, Stroll admitted that tire pressure was not the team’s problem in qualifying: “I think it was different,” said the Canadian.
“We have to look at why we were so slow. I’m not quite sure why we’re so slow.’