It's funny how things work in show business sometimes.
After The Mary Tyler Moore Show ended a 7 year run, Ed Asner's cranky Lou Grant was spun off into his own series, which would be the last spin-off, after Rhoda & Phyllis (Betty White's self-titled series was not a spin-off, as she didn't continue as Sue Ann Nivens), except that Grant was a drama. By that same token, for what it's worth, Trapper John, M. D., while not technically a spin-off from M*A*S*H (because of a different actor in the role), also went the dramatic route instead of continuing in a sitcom or dramedy format. Both of those series had decent runs.
Moore, on the other hand, wasn't so lucky. She transitioned to trying a variety show, hoping to follow in the ratings path of her friend, Carol Burnett, who had ended her series a few months prior to the launch of Mary. Moore retained writers Tom Patchett & Jay Tarses, who had worked on her sitcom, and built an ensemble that included James Hampton (ex-F-Troop, The Doris Day Show), Dick Shawn, and a couple of future stars in Michael Keaton and David Letterman. Mary was even given Ed Sullivan's old time slot at 8 (ET) on Sundays, as CBS was cognizant of the fact that ABC had tried and failed with two variety shows in as many seasons in the 7 pm slot with Bill Cosby and the Brady Bunch, and, as memory serves, Donny & Marie moved to Sundays to finish its final season.
So where did Mary go wrong? I can't rightly say, since I never saw the show. CBS would later build a comedy block on Sundays that would remain intact well into the 80's, but apparently, variety shows were slowly dying out, and weren't feasible or viable on Sundays anymore. Fellow blogger Ivan Shreve would probably find an excuse to blame the charismatically challenged Hampton, but he was just one piece of the puzzle, as was usually the case in his career.
There won't be a rating, so we'll leave you with the series opener.
Should've saved the monologue for someone like Letterman, Mary.