Red Bull motorsport boss Helmut Marko says that data collected in the latter part of 2018 showed that Max Verstappen had clearly moved ahead of Daniel Ricciardo in terms of outright speed.
Ricciardo appeared to have the upper hand over his team mate at the start of last year's campaign, with the Aussie winning in China and Monaco while Verstappen came under fire for a series of mishaps and mistakes.
However, the Dutchman eventually got his act together, consistently outpacing Ricciardo in qualifying while the latter's performance was also impacted by a string of mechanical issues.
In the end, Ricciardo chose to leave the Red Bull family and move on to Renault, a move many believe was motivated by the Honey Badger's realization that remaining alongside Verstappen would permanently put him in his team mate's shadow.
"There is specific data," Marko told Autosport.
"In qualifying the gap to Ricciardo is greater. In the race he’s also a bit faster.
"The strange thing is Max sometimes slides more, but still manages to keep the tyres alive. That has developed. When he came to us, it wasn’t like that yet.
"In the second year [2017], Ricciardo dropped back a bit, but he recognised that and then he worked intensively with his physio and other things on himself, so he came close to Verstappen again.
"But in the second half of the 2018 season Verstappen has clearly moved away."
Verstappen also benefitted from his maturing process, the 21-year-old tempering his on-track approach but without losing any of his speed.
"The basic problems were a certain lack of control and impatience," added Marko.
"The point is Verstappen is fast enough. He doesn’t have to constantly prove that he’s the fastest.
"He doesn’t need that. He already has an image in the duel that it’s better not to mess with him."
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