Off the back of competitive showings in the United States and Mexico, and returning to the scene of its 2022 triumph, Mercedes had hoped for another strong outing at Interlagos.
But it endured one of its least competitive weekends of the year, with Lewis Hamilton and George Russell struggling for speed in qualifying and then being well off the pace in the race.
Russell managed fourth in the sprint before retiring from the grand prix, while Hamilton grabbed a seventh in the sprint and finished eighth on Sunday – but more than one minute behind race-winner Max Verstappen. Mercedes-powered customers McLaren and Aston Martin both finished on the podium.
Wolff said the lack of performance shown over the weekend was confusing, and not something that the squad should simply brush off.
“Swings [of performance] are on, but swings are not on from being almost quickest to being wherever we ended up... eighth,” he said. “For me, personally, the worst weekend in 13 years.
“Totally baffling. At the same time unacceptable for all of us. We are a proper structure, solid team and that didn't look like a solid team.
“Within three consecutive races you're finishing a strong second, and both of them challenging Max, and then a week later you're ending up nowhere. I believe this is just not on.”
Source: Autosport