In OOTP, there is a hidden coefficient called Talent Change Randomness. Its only purpose is to create unpredictability in player development. However, the effect is not evenly distributed and does not have the same effect for every player. It is still expected that the majority of talents will become top players, but this coefficient makes the difference between a player who is considered to have a potential of 160 to surpass expectations and reach 180, while a player with a potential of 180 to only reach 150. Additionally, although rare, extreme examples can occur, such as the emergence of late bloomers like Vardy or some players who have shown great talent and suddenly decline due to unknown reasons, like Dele for example. All of this is possible and happens completely randomly in OOTP with each loaded save. However, the randomness in potential are not so widely extreme that you can win the Champions League with the original Weymouth team. It is possible for one of their players to develop into a decent Premier League player, but that's the best you can hope for and it is unlikely to happen more than once in 50 different save games you start.