I guess what the OP is saying is if Anderson loses does it really mean he isn't a better fighter than Vitor?
Would a 'prime' Anderson Silva win this fight?
I can sort of see the point but of course it wouldn't be an 'excuse'. The question to me is legacy. If Anderson loses, I can see him retiring at MW or retiring altogether, but I couldn't say his legacy wouldn't be that of the greatest MW of all time just because he lost one fight later in his career.