"Top performers" is a very relative term. It all depends on your traffic sources, and the demographics you are pushing through the offers. The list of top performers you are given do perform well when averaged out across all affiliates in the network, but it's no guarantee of success for you.
For example, if a "free ipod" offer is converting at 20% across the board on a network, you certainly won't get that if you are pushing non-targetted pop-under traffic.