Silva is one of their best draws now.
129 had GSP/Shields, Aldo/Hominick, and Randy/Lyoto and did 800k. 126 had Silva/Belfort and Griffin/Franklin and did 725k. They just can't put him against someone no one believes can put up a fight against him. GSP dominates but he is doing it with point fighting so he is viewed as more vulnerable than a guy who slaughters almost everyone he faces.