I think fedor still has it in him unlike most people. I like both fighters but im giving the edge to Fedor because of his speed and power. I think he is going to have a hard time with silva though. hes a very tough guy and it'll be hard to knockout or even tko him. on the ground the advantage I think should go to bigfoot. He has a solid ground game.
Did I misread your post... or did you say Bigfoot has the advantage on the ground?
Fedor will definitely win this fight where ever he wants. Silva is definitely a great fighter but his ground game is less than spectacular. I doubt he could submit or GnP Fedor to inflict significant damage.