Mercedes' "Achilles heel" was exposed in Austria, team boss Toto Wolff has admitted.
"We knew it would be a difficult race for us," said Valtteri Bottas. "In the end it was even worse than we expected."
After a run of eight consecutive wins for Mercedes, it was Red Bull and Ferrari finishing one-two in Austria as the silver cars battled to control overheating.
"We already opened the bodywork as much as we could. The only other way to get the temperatures down was lift and coast," said Wolff.
"We knew we had a problem with the chassis cooling, that is our Achilles heel. But when we lose, that's really the best way to learn."
Lewis Hamilton, the runaway championship leader, said he was also surprised how much Mercedes had to slow down to control the overheating.
"The others went through the race at full speed, just as should always be the case in Formula 1," he said.
"Fortunately, there are not many hot races like this. Maybe Hungary or Mexico."
Boss Wolff told Canal Plus broadcaster that Hockenheim might also be a problem for Mercedes.
"At least I'd like to say bravo to Pirelli," he said. "After all this talk about the tyres, we managed to see two great young drivers fight until the last lap," he said.
"But in my heart I was upset that we could not defend ourselves here, let alone attack. We had to lift and coast for 400 metres at a time to cool the car.
"That's rolling around, not racing. But while it was not a good day for us, it was a good day for Formula 1.
"Just as there are good and bad football games, it is obvious that Paul Ricard was not a good track layout for spectacular racing, but Spielberg made up for it," said Wolff.
Arguably the most disappointed figure on Sunday was Ferrari's Charles Leclerc, who - as in Bahrain - almost won his first grand prix.
Boss Mattia Binotto warned that Austria was a good opportunity for Ferrari amid an otherwise challenging season with its 2019 car.
"Can we fight like that on all the tracks? I don't think so," he said.
"There are several circuits ahead where we will have a harder time, but we had a few new parts here that worked and we will keep preparing new ones all the time."
