Few would nominate Fistful of Dynamite as Leone's greatest film, though many might herald it as his most underrated. Leone did not intend to direct it and did not bring the same concentration to the film that he did the others. By this time Leone had entered the last phase of his career, a 20-year Puccini-like period of vacillation during which he found it very difficult to settle on a project and pursue it with confidence and efficiency.
Can you tell me why the past perfect is used in my excerpt. Leone entered the last phase of his career after the mentioned movie (Fistful of Dynamite) having been realized. Could it be sufficient just the simple past?