There was a 10% drop in the overall US ratings for the season after Patrick Duffy left. But worse, there was a marked decline in the ratings during the second half of the dream season, when the show dropped out of the top 10. That’s what alarmed CBS. The overall rating for the season was boosted by strong numbers in the earlier part of the season, plus a strong season finale. But the ratings were dropping significantly during that latter part of the season. If the show had been doing fine, then Lorimar and CBS wouldn’t have spent all that money getting Duffy and Lenny Katzman back on board.Dallas was doing fine without Bobby Ewing, at #6 in the 1985-86 ratings, down from #2 in 1984-85. Dynasty went from #1 in 1984-85 to #7 in 1985-86. In hindsight, all the big US soaps declined in the ratings after 1985, some more than others. Knots Landing did the best in slowing their decline down, and by 1988 Knots Landing was the most popular US soap, with Dynasty having had a big decline out of the top 40, and Dallas going into a big decline of their own out of the top 20 and would soon crash much further. Bobby's return did not stop an accelerated ratings decline for Dallas after 1986.
The ratings drop between 85-86 (the dream season) and 86-87 (Bobby’s return) was the smallest drop between seasons the show had seen since the ratings started declining after the show’s peak in 1981. The overall rating between 85-86 and 86-87 was virtually identical (a little less than a 3% decline). You can attribute Duffy’s return or better storytelling to this. Then, after Victoria Principal left, the show’s ratings drop resumed - it lost almost 20% of its audience in the season immediately following her departure.
Last edited: