But the programme, described by some as brutal, has also discarded its fair share of talents, including Jaime Alguersuari who was dropped at just the age of 21.
"Those in the team who were against him (Ricciardo joining) are now silent," he added.
Indeed, at present, Ricciardo is even showing up the reigning quadruple title winner Vettel in the 2014-spec RB10.
Marko says Ricciardo confirms the Red Bull "philosophy, to give young drivers a chance to show their potential to win".
"He has shown that he can keep up with Sebastian, even under extreme pressure and difficult conditions," he said.
As well as more than 'keep up' with Vettel, Ricciardo has also improved the atmosphere inside the team, said Marko, whose relationship with Mark Webber was never good.
"The mood in the team is much better now," he said. "There is cohesion between the drivers and no more two directions."
Webber also seems to be enjoying his new life after his seven years with Red Bull, finishing on the podium at a wet Silverstone last weekend in his world endurance debut in the Porsche prototype.
"Always tastes good," the 37-year-old said as he 'tweeted' a photo of himself in his new white overalls drinking from the champagne bottle.
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