Gerhard Berger believes Red Bull accelerated the promotion of Max Verstappen in order to ramp up its efforts to fight with rival Mercedes.
The former Austrian driver, under whose guidance Sebastian Vettel clinched his very first Grand Prix victory at Toro Rosso, and who has remained a close friend of Red Bull founder Dietrich Mateschitz, considers that the senior bull outfit needs the best line-up available if it is to fight on an equal level with the dominant Mercedes squad led by Nico Rosberg and Lewis Hamilton.
"I think Mercedes have the best two drivers they can have," Berger said, speaking to Motorsport.com.
"I think the other teams are realising that if you want to beat Mercedes, when they have a big technical advantage, and especially on the engine, even if you put yourself on the same level, you have to beat these two drivers to win the constructors' championship.
"Because these two drivers are each in his way outstanding, and in a combination they are unbeatable.
"That's why Red Bull reacted very strongly with Max Verstappen, they said 'we have Ricciardo, somebody able to compete, but we need another one, because they have Nico and Lewis.'
"They thought: 'If we get Verstappen and Ricciardo we can at least put Ferrari under pressure, and next year we have a chance to compete with Mercedes with two big guys'."
Berger also underlined the quality of Red Bull's RB12 chassis, which he currently considers the best chassis in the field, and one which has brought the Milton Keynes outfit back to the forefront.
"I think at Red Bull you feel a very big dynamic going on. You know, in F1 you always have these cycles - three years very strong, or four years very strong, and then it's going down.
"It's important not to lose many of your key players at this time. And I think Red Bull managed very
"They always knew that Renault had to do their homework, and it looks like Renault are doing something, and it looks like the steps are forward.
"Winning in Spain, even if Mercedes stopped, but beating Ferrari, it was already a little bit of a light at the end of the tunnel."
In the former Ferrari and McLaren driver's mind, there is no question that Verstappen is en route to stardom and a future world championship contender.
"He's still young, he still has to prove everything, but for me he's a clear championship candidate in the future.
"I watched Max very closely in karting, because my nephew [Lucas Auer] was racing with him. And then I watched him in F3, because I was working with the FIA.
"So the racecraft of Max Verstappen I saw before – I know he's a good candidate for the future."