1) Sonnen is a wrestler and has been cutting weight at a very young age. Don't really know why people have been saying he had a tough weight cut, it was planned for him to cut 20 pounds in a 24hour period. You don't eat coconut crusted chicken on a Thursday when have trouble making weight for the Friday.
2) Silva wasn't that badly injured to begin with, not saying his ribs didn't hurt, but if he had a severe rib injury which many seem to point out, there is no way the commission would let him fight.
3) recent performance, I can see this being a point, as Silva destroyed both Vitor/Okami. Bisping is however very underrated and he has some very good TDD.