No one ever talked about the Curse of the Bambino until 1990 when Dan Shaughnessy used the expression for a book title. There was no basis for any curse beyond a title drought, the type of which were extremely commonplace in MLB throughout the 20th century. People who cite the Curse for anything are just throwing mystical causes for simple frustration and attributing to divine forces to mask their ignorance. Cubs fans did this for years, too.
On the other hand, the cliff is based on having a really weak farm, which is the consensus of every scouting organization in existence today and will make it difficult to replace the Sox younger stars as free agency approaches.
The funny thing is more people seem to believe in the Curse than the Cliff, despite only the Cliff having evidence that it exists...