Daniil Kvyat is back in Formula 1 because he "changed".
That is the view of Dr Helmut Marko, who has decided to bring the Russian back to the grid next year to replace Pierre Gasly.
'He had problems'
"It's simple - Daniil has changed.
READ: Kvyat in frame for 2019 return - Horner
"His speed was always there, but he had problems with the mental side. At Ferrari he matured with the completely different environment. He has also realised how precious it is to have a seat," said the Red Bull official.
"Maybe he went to Ferrari hoping to get a car there, but it was not possible. We always kept in touch. Daniil even called me before Ricciardo called me.
"There were not many drivers who were really eligible and the conditions were right, so I'm happy that he is back with us," Marko smiled.