The rating information for Strikeforce: Diaz vs. Cyborg shows a successful outing for Strikeforce. In fact, this is the second highest rated show in the history of Showtime's involvement with MMA. MMA Junkie with the details:
Overall, the event averaged 561,000 viewers (853,000 peak), which is more than any single Strikeforce event broadcast on Showtime in the past year.
The ranking just behind 2009's female championship fight between Cristiane "Cyborg" Santos and Gina Carano, which averaged 576,000 viewers (856,000 peak) for the card.
There are probably a few factors at play here. First of all, Diaz is a very solid draw for Strikeforce. Regardless of anyone's feelings on the level of competition he is facing, he has the kind of personality and fighting style that draws in viewers. Strikeforce has also been a strong presence in MMA news with their heavyweight tournament making huge waves. We'll see if they can carry this momentum into their next event.