Aleix Espargaro admits he is "very angry" with how his 2020 MotoGP season on the Aprilia went as the marque "never proved" it was close to the leading bikes.
Aprilia overhauled its RS-GP MotoGP bike for the 2020 season, with Espargaro believing podium challenges were a possibility after strong showings in the Malaysia and Qatar pre-season tests.
But Aprilia never came close to fighting for the podiums, with the closest Espargaro got being at Brno when he ran inside the top three for the first lap-and-a-half.
The Aprilia spent much of the season running with a detuned engine owing to mechanical issues at Jerez, while numerous technical issues plagued Espargaro.
And while the best he could manage in 2020 was eighth at the Portuguese Grand Prix finale and 17th in the standings, Espargaro always maintained the current bike was the best he'd ever ridden at Aprilia.
He will remain with the squad for at least two more seasons, but admits he came close to retiring during the COVID-19-forced lockdown before Aprilia offered him "a very good contract".
"This winter when I was a lot of time at home with my wife and my kids during this COVID lockdown, I was ready to retire," Espargaro said when asked by Autosport how he approached the next phase of this Aprilia project.
"I was very happy at my home with them, I have many things to do in Andorra.
"So, I was prepared and I decided with [my wife] Laura that if the time [to retire] was 2020, it was welcome.
"But after the pre-season test, I felt very, very good with the bike. Then Aprilia during the lockdown offered me a very good contract and I decided to stay to prove we could put the bike on top.
"Sincerely, I'm very angry about this season, very angry, because we never proved the bike is close to the top bikes and there is still a lot of jobs to do.
"But [in Portugal], the pace we did you cannot do if the bike is not good.
"So, still it's the worst bike of the grid but by nothing. We are very, very close, so I think next year is crucial for us.
"Next year is crucial. For Aprilia and for myself, next year we have to fight for top six.
"If we cannot be fighting for the top six in every race, it will not be a good year at all."
Espargaro has already ridden the first 2021 prototype RS-GP at a private test at Jerez immediately after the Portuguese GP.
As per the concession rules, Aprilia is the only manufacturer allowed to upgrade its engine in 2021 - although KTM can start the season with a new engine design, having lost its concessions this year.
Espargaro's team-mate for 2021 is still unknown at this stage, with Aprilia revealing last month it will decide after testing to promote either Bradley Smith or Lorenzo Savadori to a race seat.