Joan Mir couldn't conceal his disappointment at fading five-seconds from a trio of Ducatis that dominated Sunday's MotoGP season finale.

It meant the Suzuki rider, who split Francesco Bagnaia, Jorge Martin and Jack Miller until lap 19 of 27, finished his title defence without leading a single race lap this season, let alone a victory.

"I don't know how to start. I'm really disappointed. I didn't expect these feelings on the race. I thought that this time could be our day, we worked very well during all the practice, but realistically I was there during the race but there was nothing I could do," Mir said.

"I was struggling a lot with the front, a lot. Our grip was not fantastic, and I didn't have any advantage to fight with them. So it's frustrating, because it's not the position I want to be, fighting for podiums, I want more. It's a difficult situation for me again."

Mir not only faced the usual problem of trying to overtake the much faster Desmosedicis, but was surprised that – unlike last season – they got even stronger as the race went on.

"Before when I was behind them, especially last year, I could see some weak points," he explained. "Last year when they started with all that power, it was massive. [But] then at the end of the race, they were struggling to turn the bike a bit more than us, and also on acceleration when the tyre was getting more used.

"[This time] I didn't see any loss of performance in the last laps, for me it's the opposite. They are even stronger on the end of the race. So it's not easy to understand.

"I don't see any weak points, and this is something that I'm worried about. And they are able to be fast with a lot of different styles. So we have work to do if we want to fight again next year, because for sure they will be really strong."

The Spaniard also highlighted that while he suffered with the usual front tyre issues when tucked in behind the Ducatis, they didn't seem to be affected.

"If you are behind one, you normally heat the front tyre more and you can have trouble. But they don't have this problem! So this is what I don't understand. It's very difficult, very difficult. Honestly, we have a lot of work to do."

Mir then compared the race times from 2020 and 2021 to illustrate his concern.

"It's very curious, because when I won the first Valencia race in 2020, we were 25 seconds slower [than today]," he said.

"Then in the second race [last year], with more information on track, Morbidelli won in front of Jack, and they finished the race in 41 minutes and 22 seconds.

"[This year] I finished 2 seconds faster than that race. But somehow, they made some improvement to be 15 seconds faster – Jack less, of course, but the others even more."

Mir's figure of 15-seconds seemed to be compared to last year's race time by former factory Ducati rider Andrea Dovizioso, in eighth, with Miller having been seven seconds quicker than 2020.

"It's something that is a huge step that they did if you analyse well. We have to work, we have to work," Mir repeated.

Failing to win a race during his season as reigning champion was naturally a bitter blow.

"It's true that I didn't win, but what nobody can say is that I didn't get 100% of the bike," Mir said. "And also, inside of me, I'm really disappointed, but I will sleep well tonight, and during all the year, because I couldn't do it better.

"It's difficult also for [Suzuki]. I understand 100%. But if you have inside your team a winner, also it's difficult to manage for him, all the pressure that I put on myself during all the season was huge.

"Also, I think that from this situation that Suzuki lived this year, we will be stronger in the future. Because this year they realised many things, about how difficult it is winning in MotoGP."

Mir and Suzuki now turn their attention to 2022 and this week's official test at Jerez.

"It's frustrating for me. From the other side, I also have to say the improvement that Suzuki is doing makes me really happy. This is something that we can see on paper, we can feel in the box, and for sure we will fight hard in the test.

"The most important thing is not to be fast in the test, that is important, but the most important thing is the information.

"We have to do a lot of laps, Suzuki will bring the two test riders they have, Tsuda and Sylvain, and they have also things to try at the beginning of the test and everything, and then we will try the things that matter more, there are a lot of things, thankfully, or hopefully. And we have to focus in many areas.

"The interesting thing about this test is that we didn't have just one or two things to try, we have plenty of things to work on the details of the bike.

"I think we have margin to improve this year for the next one, and we for sure will try chassis, we will try the aerodynamics side, we will try the engine, because it's not frozen any more.

"And this is really important. It's even more important than this race, which was super important. But to give good information and to give the correct feedback to our engineers, it will be the key for next year."

While Mir had already confirmed third place in the world championship, with six podiums, team-mate Alex Rins crashed out for the sixth time this season and finished in just 13th overall.

"Unlucky race in Valencia for sure. It's a big shame to finish the season like this, because the pace was there," said Rins, who was ahead of his team-mate in third when he fell.

"I made a mistake, I was a little bit wide, and crashed because I wasn't on the correct line. The pressure of the brake was good, but I had a bit more angle.

"The important thing is that we analysed the crash in the box and we discovered why I crashed. Let's see, let's learn a lot from this year to go on to the next one.

"It was quite difficult behind Pecco and Martin, but let's finish this season and go to the Jerez test to try a new bike and to see if we can fight for the next year."