McLaren Racing Director Eric Boullier has admitted that their form this year seems to be dependent on the weather conditions.
Both Jenson Button and Kevin Magnussen failed to finish in the points this week in Shanghai, where their lack of downforce, in the slow corners particularly, was brutally exposed.
This is largely due to McLaren's small operating window in terms of temperature, during which the tyres provide optimal levels of grip.
"We are missing downforce, so we cannot exploit the tyres as easily as Mercedes and Red Bull," Boullier told Autosport when asked about their varied form this year.
"So it seems the performance range our car works in is weather dependent. If it is too hot we are out, if it is too cold we are out.
"What is difficult to explain is that if you look at Bahrain, except for Mercedes, we were chasing the Force Indias and we could have, with a better strategy, even finished on the podium."
After claiming two podiums in the season-open in Australia, McLaren has now failed to score points in consecutive races, although Boullier admitted last week's performance in Shanghai was far more frustrating than the race in Bahrain.
In Bahrain, both drivers retired with clutch failures after the team fiddled with their gear rations in an attempt to find more lap time. In China, though, they were just significantly off the pace.
"It is obviously bad - but it is even worse, to be honest," Boullier said of their performance in Shanghai.
"If you try something [like the Bahrain gear-change gamble] because you are under pressure that is one thing. I accept an honest mistake.
"I don't accept it because something went wrong, but you can make this kind of mistake. But to have a DNS (did not score) - that hurts."