Originally Posted by billnepill
So it's not all about contrasting styles as you threw in there a couple more factors- Excitement and competitiveness.
Let's take the "pigeon" and excitement part. In hindsight you could argue that the outcome of matches is easy to predict but in 2008 I doubt you would say that. At that point the h2h was 8-6 and the rivalry looked promising. Nadal and Federer are the biggest tennis stars by far and their encounters never lacked excitement and a lot of hype. In my view there is a bigger picture to a rivalry than h2h as well. Those players battle for the number 1 position and overall domination of the sport. The way they play, practice, what they focus on in their game etc it's partly done to beat their rival. That made Nadal become a better player on all surfaces and he finally got to Federer on the big non clay events.
Therefore, I view your criteria for a rivalry as too simplistic and your evaluation of Fedal as an understatement. However, I agree that contrasting styles is an important consideration albeit perhaps not be most important one.
It's not a be surprise that NadalAgassi always put down Federer, as usual.
Many fans believe Fed/Nadal is one of the greatest rivalry.