Why is what?
I never understood the whole fuss about Diego, I never saw him make the team stronger, I never saw him take things on his responsibility, I never saw him finish matches, I never saw him what many are making him to be. He is a good player, he can do the team well but he is far far far from being a key player that makes a difference. If the team is not strong, Diego would not make an addition, we all saw how he was forced to track back and once he does that he disappeared. We all saw how easily he was marked and played out of the game, we all saw his free kicks.
Sab said it millions of times last season, Diego is a player that has to have the whole team working for him in order to produce and she was right. So tell me, why create a whole team for one player and when this player is injured or suspended the team would stop functioning? Why create such a team and when it's time to sell the player you have to start all over again?