Red Bull motorsport boss Helmut Marko admits his move to hire Brendon Hartley was 'out of the norm' compared to his usual standards of selection.
Dany Kvyat's persistent under-performance coupled with Carlos Sainz's late move to Renault opened the door for a complete rotation of drivers at Toro Rosso, with Hartley and Pierre Gasly promoted to the Faenza-based squad.
Hartley's profile as a works sportscar driver with Porsche - however successful he was - and his age certainly did not position him as a likely candidate, but the Kiwi's persistence and a dose of boldness on Red Bull's part brought him the unexpected drive.
"I can only say Red Bull is different, so why not have a mature rookie? And we didn't have any of our junior drivers ready, so we started to look around," Marko told Formula1.com.
"The fact is Brendon looks like a twenty year old, maybe we even could sell him as a teenager!
"Nevertheless, yes, hiring Brendon was out of the norm - a different story - and we are happy with him."
After a difficult season, and following its complete driver turnaround and the switch to Honda power, Toro Rosso starts the year from a clean slate.
Gasly and Hartley passed the litmus test in the final races of the season however, and Marko believes the team's driver line-up has shown promise.
"Toro Rosso started reasonably, then they ran into unbelievable reliability problems... unbelievable!
"Also in terms of the car development, it was not what it should have been," Marko admitted.
"Now they are focused on next year and their cooperation with Honda. Since the announcement all their efforts have been going into that.
"The drivers? All the drivers the team started the season with were gone at the end!" he laughed.
"Sainz is loaned to Renault; Kvyat is gone, so Toro Rosso had to restart in mid-season with two blank pages.
"I think for the circumstances Gasly and Hartley did really well," he says.
"And the good news is that Brendon doesn't have to switch anymore between Porsche and F1, so I am sure for next season Toro Rosso has a very promising driver line-up."
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