i think that amount you posted applies to RPM, which is "a varying average of what the domain/portfolio would earn per 1000 visitors, with all other statistical variables remaining stable".
last year portfolio avg @ voodoo, rpm = $17 > highest individual domains' rpm = $800
last year portfolio avg @ ds, rpm = $53 > highest individual domains' rpm = $3,735.00
last year portfolio avg @ :sedo: = $5 > highest individual domains' rpm = $770
so for those three, overall RPM average is $25
I don't understand how anyone makes money with them.