Ryan had written the part of Mackey for someone with a young Harrison Ford personality. Due to the complexities of the character, he was uncertain they would have found a suitable actor for the role, and cast his own doubt on his writing. During casting, Ryan had been surprised with Michael Chiklis's audition. Chiklis had gained a soft reputation within Hollywood based on his roles from "The Commish" and "Daddio", and felt that he needed to have a change of pace in future roles, as he was finding himself cast for older, overweight parts. Chiklis spent six months away from acting and losing a significant amount of weight, and for his audition on "The Shield", had shaved his head. Ryan was taken by this new appearance feeling it wasn't appropriate, but found that Chiklis had a certain charisma in his delivery that worked well into the Mackey character. This allowed Ryan to write Mackey as a compassionate figure, able to get away with certain improper actions through his charisma, which served to draw fans to sympathize with Mackey throughout the series. Ryan recognized that with Chiklis as his star, it validated his success as a writer.