Pierre Gasly deserves "some of the blame" for the failure of his time at Red Bull's top F1 team last year, according to Dr Helmut Marko.
The Frenchman has expressed some unhappiness with the way his demotion to Toro Rosso was handled, revealing that "some promises were not kept".
But boss Marko told motorsport.com's Russian edition: "It seems to me that Pierre should take some of the blame.
"He came to Red Bull and saw only one goal in front of him - Verstappen," he said. "No one else.
"If he had accepted from the very beginning that Max is still faster, and tried to gradually get close to him - but he tried to change his style, tried to reduce the gap in other ways, change something, try to attack harder. And this led to complete failure," said Marko.
"However, his return (to Toro Rosso) was amazing," he insisted.
Indeed, Marko said Gasly coped with returning to the junior team from Red Bull Racing a lot better than Daniil Kvyat had some years before him.
"At such moments, you understand how important psychology is," Marko said.
"If I would have said that I expected such a return from him (Gasly), I would be lying. But unlike Kvyat, who was completely broken, Gasly blossomed. Which was fortunate for himself and for us too.
"Pierre returned to Toro Rosso and instantly became the same Gasly that we invited (to Red Bull).
"I think he learned a lesson and made the right conclusions from those six months at Red Bull. I think he can achieve a lot in the future," Marko added.
He also rejects the notion that Gasly was dumped or 'demoted' by Red Bull.
"We are talking about Formula 1," said Marko. "Do you know how many thousands of drivers dream of getting a place here?
"He still makes a lot of money, and is still in the best championship in the world. I would say this is a chance, a new opportunity, but not a downgrade."
And while Marko is happy with Gasly at Toro Rosso, the same may not be true of the more experienced Kvyat, who got his Red Bull demotion back in 2016.
Asked if the Russian can still hope for a future return to the top team, Marko said: "Yes, I think so.
"He still needs to add consistency, but he had a very strong last race in Abu Dhabi.
"The podium in Hockenheim was also great, but if we talk about laptimes and how he worked with the tyres, then Abu Dhabi was his best race of the season."