The six-time world champion continues to struggle for form on the radically overhauled 2022 Honda and could only manage 10th on the grid in qualifying.
Ahead of the race, Marquez felt his pace was good enough only to battle for the top seven at best, with the Spaniard crossing the line sixth having let Pramac's Johann Zarco go ahead on purpose.
But had it not been for crashes for both Suzuki riders and long-time race leader Francesco Bagnaia, Marquez would have finished down in ninth.
When asked by Motorsport.com if he could have had a strong race without riders falling ahead of him, Marquez replied: "No, our position without the crashes was ninth. But three riders crashed, but we finished sixth. I was not able to be faster.
"When Zarco overtook me, I just went wide in a purposeful way to not lose time, I let him pass and tried to follow him in some laps. But I saw he was faster. I didn't have the speed, so I just finished the race."
Marquez had a big moment during a practice start in warm-up which tweaked the right arm he badly broke back in 2020.
This ultimately didn't cause him too many issues in the race, but he concedes he was physically not well on Sunday.
"I got up and I didn't feel well – body, but also the arm," he added. "Even like this it was the race day, so you need to race.
"In the warm-up I was struggling, I got into the box, I go out for the practice start and I had that strange shaking. There was pain a little bit [in] the arm, but nothing wrong. For the race, it was OK, was in a normal level like Jerez and Portimao.
"We started and we did our race. Constant, solid race. Nothing crazy, but [that] was our pace.
"So, I stayed in my pace and I finished sixth. I said our position was between fifth and seventh, three riders crashed in front, then we achieved our target that was between fifth and seventh."
Once again Marquez was the top Honda rider, albeit over 15 seconds from the race win, which he says proves there is performance in the bike – but he is not riding it well enough to extract the best from it.
"Riding, I'm not in my sweet moment," he said. "I was riding much better in the past. I am riding in a different way, in a strange way in the beginning but I am getting used to it.
"It's true that I'm not riding like I want. I always try to force my riding style to what I need.
"But it's true I'm not riding in my best level, but every race I am the best Honda. So, it means the performance is there but I'm not riding well."
