Time magazine called Shelley's departure “probably the greatest career stumble in show business history,” and TV historians agreed that Shelley's move to leave ranks up there with Pernell Roberts' decision to leave “Bonanza” and MacLean Stevenson and Larry Linville's departures from “M*A*S*H.”
During her final season, Shelley told People magazine, “It's time to move into the next phase. I've studied the question [of leaving 'Cheers'] carefully because that was only fair to me and the 'Cheers' people and the fans.
“I know many of them have made their displeasure known, People who work on the show have said their friends told them, 'You tell Shelley that we're really disappointed,' And I feel bad because it's going to be hard not to see Diane with Sam.”
The book “Toasting Cheers” said Shelley “experienced tension and hostility from the cast. At times they treated her like she was going to die, and near the end she was treated like she was Diane.”
Crew members complained that she was difficult on the set. One insider said, “It wasn't Shelley versus Ted, it wasn't Shelley versus the cast, it wasn't Shelley versus the crew. It was Shelley versus everyone.”
Danson admitted to People magazine before Diane's finale that “The relationship [between Sam and Diane] was beginning to slow down. I think it's wonderfully appropriate on all levels that Shelley decided to leave. I think the relationship had been done.”