New info
I was told that the results from both the 2013 Carpet and Asphalt Nats are used to determine the qualified drivers for the 2014 Worlds.
The number qualified from each event is determined by calculating the percentage of the total number of entries from both events. So if you get 20 entries at each event, 10 from each would qualify to make the 20 person team.
The ROAR team gets 20 spots plus 10 more for being the host venue. ROAR also get unused spots. There could easily be 50-60 spots for ROAR drivers which means that all these spots probably won't be taken anyway.