Yuki Tsunoda "would have deserved" a promotion to Red Bull Racing, but lost out to Liam Lawson in key areas.
That’s the explanation of team advisor Dr Helmut Marko, as Red Bull announced that rookie Lawson, 22, and not the much more experienced Tsunoda, will be replacing Sergio Perez for 2025.
Marko says the Japanese driver took the news well.
"He’s in Japan right now and I spoke to him on the phone," Marko told f1-insider.com. "He took the news relatively calmly.
"I told him to keep pushing hard with the Racing Bulls and then we’ll see what happens. It was a positive reaction," the 81-year-old added.
Team boss Christian Horner insisted it was a difficult decision to overlook Tsunoda, but indicated that the job of being Max Verstappen’s teammate is "daunting".
The matter was discussed at length in a meeting of Red Bull team officials and shareholders in the hours immediately after the Abu Dhabi finale.
"The engineers presented comparative figures, which we used as the basis for the decision," said Marko. "In principle, it was a luxury problem - both would have deserved the promotion.
"But Lawson may have more room for improvement in the future. His mental strength in particular was the deciding factor in the end."
Horner also noted that Lawson’s "pace was a little bit better" than Tsunoda’s as they went head-to-head over the last part of the season at Racing Bulls (RB).
"What struck me most about Liam is that you put him in a tough situation and he copes. He has a tough racing mentality and he’s not afraid to fight wheel-to-wheel and even use contact if necessary," he added.
"So I think he will do a great job for us."
Former RB (previously Toro Rosso-Alpha Tauri) team boss Franz Tost, however, has a clear warning for the young New Zealander.
"All I can say about Liam is that he has to do his own thing and never try to compete with Max," said the Austrian. "He is far from past his prime and has endless capacity. And he now has the self confidence of a four-time world champion.
"If Liam focuses on Max’s times, it will go wrong for him. He must only think about himself and try to improve the car together with Max. Anything else would be fatal and doomed to failure," Tost said.
As for Lawson, he smiled as he explained that Marko’s notorious brutality with driver decisions has prepared him well for his new role. "Ah, the phone calls from Helmut when I was about 16," he said. "He always put the pressure on straight away.
"You just knew that if you didn’t perform, you’d be fired. That’s definitely tough, but it really prepares you for Formula 1."