Scuderia Toro Rosso principal Franz Tost says the outfit replaced Sebastien Buemi and Jaime Alguersuari because they were no longer fulfilling the team's criteria as a place to bring on rookies.
The Italian outfit caused a surprise on Wednesday when it announced that it was replacing both its drivers to hand Daniel Ricciardo and Jean-Eric Vergne race seats for 2012.
Although the move caused some controversy because of the strong performances delivered by Buemi and Alguersuari throughout 2011, Tost says that the motivation for the decision was because Toro Rosso's whole ethos is about bringing on new talent.
"Sebastien has been with us for three seasons and Jaime for two and a half," said Tost in a Q&A issued by the team. "Both of them worked hard for the team, doing their very best and achieving some good results.
"However, Scuderia Toro Rosso's ethos has always been that of the "rookie training school" and with over two seasons under your belt, you are no longer a rookie. In an ideal world, drivers would move from Scuderia Toro Rosso to Red Bull Racing, but there are no vacancies with our sister team right now.
"It might be seen as a harsh decision, but Formula 1 is a tough environment and Toro Rosso has always been very clear about the principles behind its driver choice."
Tost said the decision to axe Buemi and Alguersuari was only taken on Tuesday, during a meeting at Red Bull's headquarters in Austria.