I think fighters coming off losses can still be a super fight. I also dont think they even have to be from different weight classes.
Example would be Chuck vs Wand. Neither were champs anymore, both were past their primes, and coming off losses. The difference was people had been wanting to see that fight for years, and MMA world was rabid excited when it was finally going down
Thats why I am kind of on the fence about calling this a super fight. Both are big names, and both have their fanbases. Both have their resumes (even though Diaz's resume isnt a GSP, Anderson, Penn, Chuck, or Wand level). However this isnt a fight people have been saying they want to see for years. A lot of that has to do with Diaz's much weaker resume, lack of a top league title (yes I know he had the strikeforce WW title but that was not a very good WW division), and the fact he was never THE guy in the WW division
Imagine how geeked the MMA community would be if it was GSP vs Anderson. It would be on ESPN, UFC would be hyping it from the day it was announced to the day of the fight, there would be tons of threads started every day about it and people dissecting everything little thing each fighter did leading up to the fight. It would destroy PPV numbers.
That would be a super fight to me anyways.
If people want to call Anderson vs Diaz a super fight then ok thats cool, but it is a much lesser quality super fight than Gsp vs Penn and Chuck vs Wand.