Mercedes F1 boss Toto Wolff called his team's performance in qualifying at Spa "unacceptable" and the worst Saturday afternoon session he's experienced in 10 years.
Just one race after George Russell's remarkable pole position at the Hungaroring, the Briton and teammate Lewis Hamilton were a pale shadow of the duo that had performed so well in Budapest, with the pair qualifying respectively P8 and P7.
But it was not the result that confounded Wolff, but the silver arrows' massive gap in the session to Red Bull pacesetter Max Verstappen.
"You can't be on pole three weeks before, albeit for very different conditions, different track, and then be 1.8 seconds off the pace at the next one," commented the Austrian.
"So there's something which we totally don't understand, or seem to get right.
©Mercedes
"Clearly, Red Bull is here in a league of their own, as the next Ferrari is eight tenths off. But that is no consolation.
"It's for me the worst qualifying session that I had in 10 years. And irrespective of what positions we're going to start tomorrow, being on pole the previous weekend and three weeks later being nowhere, it's just not acceptable for ourselves."
Hamilton and Russell will line up fourth and fifth on Sunday's grid thanks to grid penalties handed to Verstappen, Charles Leclerc and Esteban Ocon.
Ahead of this weekend's round of racing at Spa, both Hamilton and Russell had high hopes of extending in Belgium their team's improvement of late. And both drivers were puzzled by the significant shortfall.
Mercedes' struggle to understand the deficit was particularly frustrating for Wolff.
"I mean, if we would understand, we could tune it," he said. "But the car is draggy in a straight line. Lewis said it was like dragging a parachute behind him.
"It is unstable on the rear. It understeers through [Turns] eight and nine. It bounces through the high-speed and gives no confidence.
"I mean, there is not a positive that I heard about how the car performs here this weekend and throughout the weekend. So I think now it's time to consolidate and decide what to do next year."
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