Why was Brad Pitt disappointed with Troy?

Could you elaborate on why Brad Pitt expressed disappointment with his role in the film Troy? Was it due to the creative direction taken by the filmmakers, the script, or perhaps his own performance? Did he feel that the character's portrayal didn't align with his vision, or were there other factors at play that contributed to his dissatisfaction? Understanding the reasons behind his disappointment could provide valuable insights into the challenges faced by actors in adapting historical figures for the big screen.