What is a rivalry? The definition could vary from person to person, and for many, it requires that the parties involved in said rivalry represent a relatively equal status, if not generally, then at least within the scope of the rivalry itself.
For example, prior to earlier this season, the Pittsburgh Steelers had beaten the Cincinnati Bengals 11 straight times. Is that a rivalry? They have certainly played from very heated and close games within that span of time.
Within the past decade, the Steelers have a 17-3-1 record against the Cleveland Browns as well, and two of the three games that the Steelers lost were games started by Charlie Batch and Mason Rudolph.