The character of Tony Scali was supposed to be in his late thirties. Michael Chiklis was actually 28 years old when cast as Scali, in part because he looked much older than his real age. When Chiklis lost weight during the course of the series, the network, fearing that such weight loss might negatively effect the ratings, reportedly had Chiklis stuff his clothing to appear older and heavy set. Chiklis was also discouraged from shaving his hair off to look still older.
Creator Steve Kronish wanted to cast Michael Chiklis after working with him on Wiseguy (1987). But CBS rejected him because they felt Chiklis was too young for the part. Kronish took the idea to ABC who was convinced to cast Chiklis after seeing him in the failed ABC pilot Maverick Square (1990).