Newly-promoted factory Ducati rider Jack Miller "looked like he was in his first or second year" of MotoGP when he first joined the Pramac squad in 2018, according to team boss Francesco Guidotti.
Last week, Ducati announced it would be promoting Miller to its works line-up in 2021 off the back of an impressive 2019 campaign for the 25-year-old with Danilo Petrucci set to depart from the factory line-up as a result.
Miller already had three seasons of experience in the premier class under his belt when he joined Pramac, having progressed to MotoGP directly from Moto3 in 2015 as a Honda protégé and spending one year at LCR and then two seasons at Marc VDS, the first of which yielded a shock victory in the Dutch TT at Assen.
However, Guidotti said in an exclusive Autosport interview that this experience didn't show when the Australian first entered the Ducati fold, as he praised his turnaround that ultimately earned him a shot at the Italian manufacturer's factory team.
"We saw immediately at the beginning of the season he arrived as a changed boy, more mature and more solid," Guidotti said of Miller. "This was also reflected in his professional aspect.
"No disrespect to anyone, but honestly when he came to us in 2018, even though he had already done three years of MotoGP, he looked like he was in his first or second year.
'Where he was before, obviously, they left him to look after himself. He was very young and probably hadn't been followed too much.
"When he came to us we understood that there was a bit more work to do than we thought. But he was also good at assimilating things quickly and understanding what the important things were.
"It was not an easy first year, there were also some quite strong verbal clashes, but with the utmost respect, because we have always believed in his talent and potential.
"He understood that these disagreements were aimed at growing together and not to throw blame on him. From then on I think he also understood the work system a bit and worked with his manager Aki [Ajo] at home to improve on some aspects he needed."
Miller concluded the 2019 campaign eighth in the standings and only 11 points shy of factory counterpart Petrucci, having scored four podiums and qualified on the front row three times in the final 10 races.
While Guidotti praised his rider for his performances last year, he equally made it clear that a "big leap" will be required for Miller to cement his place as a works Ducati rider.
"He also made quite a few mistakes, but it was also the first year that he was constantly in the positions that matter," said Guidotti. "It was a new situation for him and he found himself making that little mistake a few times that could ruin the result a bit.
"Toward the end of the season he became very consistent, but it will not be enough for the factory team. These podiums and these front rows are important in a satellite team, but the goal in a factory team is different, so he will still have to make a big leap."