Silva would get spanked by Machida anyway, so he prolly wouldn't take that fight anyway if they weren't team mates. So far his opponents at higher weight classes have been tailormade for him. He even wants to fight Mir at HW instead of one of the high caliber strikers or wrestlers, although I still see Mir beating him.
Not saying Silva is scared to fight Machida or anything because he isn't exactly the only person in ufc not fighting team mates, but one has to admit that he hasn't really fought a guy with high level wrestling & jitsu or atleast high caliber stand up on his trips to upper weight classes. Give Silva someone like Coleman, Rashad, Shogun, Randy, JDS, Kongo or Cane for example, because styles make fights and so far the opponents he has faced on higher weight class have been pretty much tailormade for him to beat.
At MW he does dominate, but if he plans to keep making those LHW or even HW trips I wanna see him against an opponent that actually causes him problems either with high level ground game or with hard chin and heavy hands.
Personally I wouldn't worry about it too much anyway, because Vitor's speed will soon give Silva a taste of what would happen if he actually got that fight vs. Roy Jones Jr. signed. Silva is fast and accurate, but Vitor's boxing and hand speed are on another level.
"When I land that left hook, the fight will be over." -Paul Daley (He called it!)