I'm not so sure. According to Ken Levine who wrote and directed him, the powers that be loved working with him on Cheers after he took over for another actor who had a terrible case of stage freight. I've looked into how the show occurred and basically, Kelsey wanted John Mahoney to play the father. They went out to dinner and apparently, Kelsey said to him in a humorous way to pitch the role "Will you be my father?" They then went into details and the rest is history. He was pre-approved for the role by the studio heads so he did not need to audition. Same with Jane Leeves and David Hyde-Pierce. Roz was initially played by Lisa Kudrow but she couldn't play "strong" and got bulldozed in scenes by Kelsey Grammer. They got Peri Gilpin who was (I think) their 3rd or 4th choice.