Bagnaia made history in 2022 when he overcame a 91-point deficit and five DNFs to secure his first MotoGP world title, while ending Ducati’s 15-year championship drought.
The Italian was criticised for making too many mistakes in 2022, but Miller believes Bagnaia has evolved beyond the rider he was in his title-winning campaign.
Asked if Bagnaia was looking better than he was in 2022 during the Portugal pre-season test, he said: "I think so.
“I think he’s looking stronger this year than in last year, even in the run he had in the back-end of the season in 2021, the run he had coming back into last season.
“I think this year he seems more of a changed man, a confident man, and he’s riding pretty impressive.
“I followed him for a very short time, I followed him through the last corner and that’s a man with confidence in his motorcycle for sure.”
Bagnaia ended the pre-season fastest of all after setting an unofficial lap record at the Algarve International Circuit on the final day of the Portugal test.
In Portugal, he stated that “Ducati and Aprilia are unbeatable at this moment”, with many in the paddock marking Bagnaia out as the firm favourite for the championship in 2023.
Miller believes Bagnaia’s main threats this season will come from within Ducati’s stable, with the Italian marque fielding eight riders across its factory squad and satellite partners.
“There’s a few Ducatis out there that are going pretty impressive,” Miller added.
“Alex Marquez, he’s adapted to that bike, he’s going to bed pretty happy most nights after the change he made.
“I think Enea [Bastianini] didn’t have the best of tests, but it’s a long season, sprint races, all that jazz.”
Miller ended the Portugal test 17th overall as KTM continues to search for a cure to the rear grip problems which dogged it last year.
The Australian – who spent five years as a Ducati rider – signed a two-year deal to join KTM from 2023 last season.
The 2023 season begins on 26 March with the Portuguese GP.
