The 2021 world champion endured a difficult day at Silverstone on Friday, finishing 10th in first practice before ending up 11th in the second session to narrowly miss out on progressing directly into Q2.
Quartararo currently sits ninth in the standings after eight rounds, with a best result of third in the United States Grand Prix and in the Assen sprint race.
Speaking after Friday's track running, the Frenchman said he had “not good balance” and was struggling to generate grip on his M1.
He explained that while he felt his riding “was quite okay", he struggled in the final chicane and overall "was not feeling super great".
“In all the other corners I felt I was riding well, but lap time was super far off what we expect so I would say the balance is pretty bad,” he added.
Quartararo was fastest in FP2 last year but fell to 11th this year, 0.6s slower than last year’s time.
Asked if he knew why, he said: “No, this is the problem. We don’t know why, basically whatever I’m doing on the bike, everything is more sensitive, I’m doing much more mistakes.
“But I’m just trying to push to the maximum and my feeling is that I’m riding one second faster than last year but I’m one second slower.
“This is what makes me feel really frustrated, because it’s not what I want and this is something that is the most difficult mentally to not know why we are that slow.”
He added: “Last year I was super fast, 2021 I was super fast, every time – in 2019 I was fast.
“But this year, every track we go that even in the past I was fast, I’m slow.
“So it’s not that the others make a step forward, but we are not even doing the lap times of the past. So this is something that we are struggling to understand why.”
Yamaha’s 2023 season has been disappointing, with the Japanese marque bottom of the manufacturers’ table.
Quartararo has complained numerous times this season that everything Yamaha tried with the new bike in the winter never worked, reverting to 2021 set-up solutions for the recent Mugello/Sachsenring/Assen triple-header.
Asked whether that said a lot about the team’s situation, he said: “We don’t really know what to do. Every time we try something it’s not getting better.
“To go in a way to be more last is not also the way. In the beginning of the year we try everything, it’s not working.
“We keep the base but yeah, basically the base of last year is the base of Assen and of here.”
