If he wants to really be in the mix for top 5 and really get his career kicking, he needs to have a good showing against Fedor for sure. However, what qualifies as a good showing against Fedor?
Rogers had a good showing against Fedor, he got brutally knocked out but he did a lot better than people expected, and look at him now. People look passed him like he's a bum, but in reality he's won all his fights except Fedor and Overeem, the two very best HW's in the world along with Cain, and he's beaten everyone else, including KO'ing Arlovski in a few seconds.
He's not a bum, he's not the best, he got beat by Overeem and Fedor, who hasn't lost to Fedor minus Werdum, and who is giving Overeem any sort of trouble these days?
My point is, even if Bigfoot puts in a good showing against Fedor, you will always have that crowd of people who will completely discredit him, and since he's in SF, that doubles.