The development of young players is immensely tricky. Different talent has different needs. Some explode onto the scene and then stall. Others are late-bloomers. More yet will look ready to take centre-stage as an elite player, only to then flounder when fame and finances flood in. It is not an easy process.
Because of this, it is also not a predictable process. Just reflect on the many young players that have broken onto the scene over the years and consider the wide range of predictions for their career. In every situation, someone will have been wrong.
To counteract this inherent unpredictability and inconsistency, clubs — and national teams, by extension — play the numbers game.