Danilo Petrucci says he "never found a good bike" across his final race weekends as a Ducati MotoGP rider, ending the Portuguese Grand Prix without a point in 16th.
Petrucci knew before the start of the season he would not be staying for the 2021 season with Ducati and will join the Tech3 KTM squad next year.
The Italian, like his team-mate Andrea Dovizioso, struggled hugely across the 2020 campaign with Michelin's new rear tyre construction - particularly how it impacted the GP20 under braking.
As a result, Petrucci scored just one top six finish all year - his wet weather win at Le Mans in October.
Qualifying down in 18th at the Algarve International Circuit, Petrucci could do no more than 16th in Sunday's race having "fought with the bike" all weekend.
"Yeah, really, really difficult, especially to finish outside of the points with so many problems and struggling a lot," Petrucci said.
"Was very, very crazy because I fought with the bike all weekend and I didn't expect, sincerely.
"I wanted to be faster but it was the maximum I could do. I never found a good pace, good feeling on the bike.
"We tried a lot, we tried our best, especially in this last weekend. I don't know.
"I always try and when I try to make a little bit more I always do some mistake. I never felt so good on this track unfortunately.
"I'm happy that it's finished. For sure I wanted to finish in a better way, but I struggled so much today to find a good feeling.
"For sure I never found a really, really good feeling. I really felt my bike just in Barcelona and in Le Mans where I was always competitive in the wet and the dry.
"In Barcelona we struggled a lot on the straight, but my main problem was the braking area all the season.
"This race, like in Valencia, we struggled with the grip and I never found a good bike."
Petrucci admits he isn't happy with his season overall due to his difficulties, but is "satisfied" he still gave his all in his final year with Ducati.
"For sure, the bike has changed a bit compared to last year, but not regarding the bike but regarding the rear tyre," he added.
This was the main thing. I'm not happy because I haven't found, except for two races, a really, really good feeling.
"But I always gave my best, sometimes it works, sometimes not. For sure I'm satisfied. Looking back, I could do much better, but I did my best."