Just two weeks ago in Bahrain, Jenson Button said the only quicker car in the field was the dominant Mercedes.
But in China, both the 2009 world champion and Kevin Magnussen were non points-scoring midfielders.
Button sounded particularly frustrated.
"I don't think (other) people brought that much (new parts) here, so I don't know what we're doing really," he said.
"Hopefully back at the factory they can stay positive and update the car because at the moment this isn't good enough."
McLaren's new boss in 2014, Eric Boullier, said he sat with Button and Magnussen after the race in China, because "they are both frustrated".
"But I can promise you that if you look at the data, you can see that McLaren are coming back, and that's what is most important," he is quoted by the Mirror.
Lauda, who is Mercedes' F1 chairman, thinks that after the depths of McLaren's 2013 crisis, the British team is now struggling for form in the wake of recent management reshuffles.
"You have to say that last year the McLaren was also not a top car," said the great Austrian.
"So you have to overcome this bad performance from last year and the new formula. If you have the new ingredients, you can be lucky.
"But if you don't have them and there is a big change with (Martin) Whitmarsh going and Ron (Dennis) coming back, these things take time to change. They don't happen overnight," Lauda explained.
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