McLaren's Lewis Hamilton and Jenson Button both called for the team to find more downforce on the car as soon as possible after they took disappointing fourth and sixth places in Valencia.
After several races in which McLaren had either looked capable of beating Red Bull or succeeded in doing so, the European Grand prix saw the Woking squad jumped by Ferrari and some way off the lead pace.
Hamilton said the team now needed more performance from its next batch of upgrades in order to close back in again.
"I think we're quite a bit down on downforce," he told television reporters. "We've not made an upgrade for several weeks now. We've had upgrades like the front wing for example but rear downforce, we've really been struggling with that."
He also predicted that McLaren could suffer more than most when the exhaust set-up rules are tightened from the next race at Silverstone onwards.
"I think in the next race we'll really, really struggle," Hamilton warned. "Once we lose the engine map [blown exhaust] I think we may see some differences there."
Button agreed with his team-mate assessment of McLaren's position.
"We need some good upgrades," he said. "We need to get our heads down and improve the car, the package. Aerodynamically I think we need an improvement for Silverstone because we're not moving forward and that's what we need to be concentrating on.
"I do know of some new parts that are coming but I think we need more. We need to take some risks because behind us is a big gap - this race anyway - to the Mercedes and the Ferraris are in front of us and the Red Bulls are miles away.
"We need a lot of laptime and I don't think this new regulation change in terms if the diffuser blowing is really going to have a massive impact - on laptime it will but in terms of mixing up the field I don't think it will. Hopefully we'll gain a little bit more than Red Bull, but I'm not to sure at the moment."
Hamilton said his Valencia race was compromised by a bad start and high tyre wear, but that the McLaren was not quick enough to do better than fourth in any case.
"It was just we got a bad start, a really very poor start, and lost out to the Ferraris but in all honesty we weren't as quick as the Ferraris so even if I was ahead of them I would have really struggled to stay ahead," he said.
"The guys [on the radio] were just asking me to stay out longer and I was like 'I'm trying to look after the tyres as much as I can so this is all I can do'. So I was pushing all the way but my tyres... I was really struggling with oversteer for a long time.
"It seems like we've taken a step backwards perhaps this weekend in terms of our performance or the others have taken a step forwards again. To be able to finish fourth, at least that's still some good points compared to the last two races I've had."
Button's run to sixth was also marred by his KERS breaking during the race.
"I didn't have a very good balance, had a lot of wheelspin, which I was struggling a lot with throughout the race," he said.
"We've taken a lot of front end out of the car and then I had the KERS fail halfway through, which for us is a lot of laptime. We have a very good KERS system and it's about four and a half tenths around a lap because you gain on exits and braking when you have KERS."